JP3592310B2 - Magnesium-based alloy wire and method of manufacturing the same - Google Patents

Description

【００５９】
【表２】

【００６０】
表１をみると、引き抜き加工前の押出材の靭性は、絞り１９％、伸び４．９％である。これに対して、５０℃以上の温度で引き抜き加工を行った本発明例は、５０％以上の絞り値と８％以上の伸びを有している。更には、引き抜き加工前の強度を上回っており、強度を上げた状態で、高靭性化が達成されている。
【００６１】
また、引き抜き加工温度が２５０℃以上では、強度の上昇率は小さい。従って、５０℃から２００℃の加工温度で、優れた強度と靭性バランスを示すことがわかる。一方、２０℃の室温での引き抜き加工は、断線のため加工できなかった。
【００６２】
表２をみると、断面減少率５％の加工度では、絞り、伸び共に低い値であるが、１０％以上の加工度になると４０％以上の絞り値、８％以上の伸びを得ている。また、断面減少率３５％の加工度では引き抜き加工はできなかった。このことから加工度１０％以上３０％以下の引き抜き加工によって優れた靭性を示すことがわかる。
【００６３】
得られたワイヤは、長さが直径の１０００倍以上であり、多パスの繰り返し加工も可能であった。また、本発明例の平均結晶粒径は、いずれも１０μｍ以下、表面粗さＲｚは、１０μｍ以下であった。さらに、ワイヤ表面の軸方向残留引張応力をＸ線回折法により求めたところ、本発明例はいずれも８０ＭＰａ以下であった。
【００６４】
（実施例２）
質量％で、Ａｌ：６．４％、Ｚｎ：１．０％、Ｍｎ：０．２８％を含み、残部がＭｇおよび不純物からなるマグネシウム合金（ＡＳＴＭ記号ＡＺ−６１合金相当材）の押出材（φ６．０ｍｍ）を用いて、種々の条件で穴ダイスによる引き抜き加工を行った。加工温度は、穴ダイス前に設置したヒータの加熱温度とした。加工温度への昇温速度は１〜１０℃／ｓｅｃ、引き抜き加工の線速は２ｍ／ｍｉｎである。また、引き抜き加工後の冷却は衝風冷却にて行った。平均結晶粒径は、ワイヤの断面組織を顕微鏡にて拡大し、視野内における複数の結晶の粒径を測定して、その平均値を求めた。引き抜き加工後のワイヤの直径は４．８４〜５．８５ｍｍ（断面減少率１９％の加工では５．４ｍｍ、断面減少率５〜３５％では５．８５〜４．８４ｍｍ）である。加工温度を変化させた場合に得られたワイヤの特性を表３に、断面減少率を変化させた場合に得られたワイヤの特性を表４に示す。
【００６５】
【表３】

【００６６】
【表４】

【００６７】
表３をみると、引き抜き加工前の押出材の靭性は、絞り１５％、伸びも３．８％と低い。これに対して、５０℃以上の温度で引き抜き加工を行った本発明例は、５０％以上の絞り値と８％以上の伸びを有している。更には、引き抜き加工前の強度を上回っており、強度を上げた状態で、高靭性化が達成されている。
【００６８】
また、引き抜き加工温度が２５０℃以上では、強度の上昇率は小さい。従って、５０℃から２００℃の加工温度で、優れた強度と靭性のバランスを示すことがわかる。一方、２０℃の室温での引き抜き加工は、断線のため加工できなかった。
【００６９】
表４をみると、断面減少率５％の加工度では、絞り、伸び共に低い値であるが、１０％以上の加工度になると４０％以上の絞り値、８％以上の伸びを得ている。また、断面減少率３５％の加工度では引き抜き加工はできなかった。このことから加工度１０％以上３０％以下の引き抜き加工によって優れた靭性を示すことがわかる。
【００７０】
得られたワイヤは、長さが直径の１０００倍以上であり、多パスの繰り返し加工も可能であった。また、本発明例の平均結晶粒径は、いずれも１０μｍ以下、表面粗さＲｚは、１０μｍ以下であった。
【００７１】
（実施例３）
実施例１および２で得られたワイヤおよび、同径の押出材を用いてばね加工を行った。直径５．０ｍｍのワイヤを用い、バネ外径４０ｍｍのばね加工を行い、ばね加工の可否と材料の平均結晶粒径および表面粗さとの関係を調べた。平均結晶粒径の調整及び表面粗さの調整は主に引き抜き加工時の加工温度の調整により行った。本発明例における加工温度は５０〜２００℃である。平均結晶粒径は、ワイヤの断面組織を顕微鏡にて拡大し、視野内における複数の結晶の粒径を測定して、その平均値を求めた。表面粗さはＲｚにより評価した。その結果を表５に示す。
【００７２】
【表５】

【００７３】
（実施例４）
質量％で、Ａｌ：６．４％、Ｚｎ：１．０％、Ｍｎ：０．２８％を含み、残部がＭｇおよび不純物からなるマグネシウム合金（ＡＳＴＭ記号ＡＺ６１合金相当材）の押出材（φ６．０ｍｍ）を用いて、加工温度３５℃、断面減少率（加工度）２７．８％の引き抜き加工を実施した。加工温度は、穴ダイス前に設置したヒータの加熱温度とした。加工温度への昇温速度は１〜１０℃／ｓｅｃ、引き抜き加工の線速は５ｍ／ｍｉｎである。また、冷却は衝風冷却にて行った。冷却速度は０．１℃／ｓｅｃ以上である。その結果、得られたワイヤは引張強度４６０ＭＰａ、絞り１５％、伸び６％の特性を示した。このワイヤを、１００℃から４００℃の温度で１５分間焼鈍し、引張特性を測定した結果を表６に示す。
【００７４】
【表６】

【００７５】
表６を見てわかるように、焼鈍によって若干の強度低下を伴うものの、伸び、絞りの靭性が大幅に回復することがわかる。すなわち、伸線加工後に１００〜３００℃で焼鈍すれば、３３０ＭＰａ以上の引張強度を維持しつつ、靭性回復に極めて効果的である。４００℃の焼鈍でも３００ＭＰａ以上の引張強度が得られ、十分な靭性が得られている。特に、引き抜き加工後に１００〜３００℃焼鈍を施すことで、引き抜き加工温度が５０℃未満でも靭性に優れたワイヤを得ることができる。
【００７６】
（実施例５）
質量％で、Ｚｎ：５．５％、Ｚｒ：０．４５％を含み、残部がＭｇおよび不純物からなるマグネシウム合金（ＡＳＴＭ記号ＺＫ６０合金相当材）の押出材（φ６．０ｍｍ）を用いて、種々の条件で穴ダイスによる引き抜き加工を行った。加工温度は、穴ダイス前に設置したヒータの加熱温度とした。加工温度への昇温速度は１〜１０℃／ｓｅｃ、引き抜き加工の線速は５ｍ／ｍｉｎである。また、冷却は衝風冷却にて行った。本発明例の冷却速度は０．１℃／ｓｅｃ以上である。平均結晶粒径は、ワイヤの断面組織を顕微鏡にて拡大し、視野内における複数の結晶の粒径を測定して、その平均値を求めた。軸方向残留引張応力は、Ｘ線回折法により求めた。引き抜き加工後のワイヤの直径は４．８４〜５．８５ｍｍ（断面減少率１９％の加工では５．４ｍｍ、断面減少率５〜３５％では５．８５〜４．８４ｍｍ）である。加工温度を変化させた場合に得られたワイヤの特性を表７に、断面減少率を変化させた場合に得られたワイヤの特性を表８に示す。
【００７７】
【表７】

【００７８】
【表８】

【００７９】
表７をみると、押出材の靭性は、絞り１３％と低い。一方で、本発明である５０℃以上の温度で引き抜き加工を行ったものは、強度が３３０ＭＰａ以上であり、大幅な強度向上が認められる。また、１５％以上の絞り値と６％以上の伸び値を有している。また、２５０℃以上での加工では、強度の上昇率は小さい。従って、５０℃から２００℃の加工温度で、優れた強度−靭性バランスを示す。これに対して２０℃の室温での引き抜き加工は、断線のため加工できなかった。
【００８０】
表８をみると、５％の加工度では、絞り、伸び共に低い値であるが、１０％以上の加工度で強度上昇が顕著であることがわかる。また、３５％の加工度では引き抜き加工はできなかった。このことから加工度１０％以上３０％以下の引き抜き加工によってワイヤが得られる。
【００８１】
得られたワイヤは、長さが直径の１０００倍以上であり、多パスの繰り返し加工も可能であった。また、本発明の平均結晶粒径は、いずれも１０μｍ以下、表面粗さＲｚは、１０μｍ以下、軸方向残留引張応力は８０ＭＰａ以下であった。
【００８２】
（実施例６）
実施例５で得られたワイヤおよび、同径の押出材を用いてばね加工を行った。ワイヤ径５．０ｍｍのワイヤを用い、バネ外径４０ｍｍのばね加工を行い、ばね加工の可否と、材料の平均結晶粒径および表面粗さを測定した。表面粗さはＲｚにより評価した。その結果を表９に示す。
【００８３】
【表９】

【００８４】
表９を見てわかるように、結晶粒径１０μｍ以下、表面粗さＲｚが１０μｍ以下であるマグネシウムワイヤは、ばね加工が可能であるが、それ以外は加工中、ワイヤ破断により加工できなかった。従って、結晶粒径１０μｍ以下、表面租さＲｚが１０μｍ以下である本発明のマグネシウム基合金ワイヤは、ばね加工が可能であるといえる。
【００８５】
（実施例７）
下記に示すＡＺ３１、ＡＺ６１、ＡＺ９１、ＺＫ６０合金相当材の押出材（φ６．０ｍｍ）を用意する。各化学成分の単位はすべて質量％である。
【００８６】
ＡＺ３１：Ａｌ：３．０％、Ｚｎ：１．０％、Ｍｎ：０．１５％を含み、残部がＭｇおよび不純物
ＡＺ６１：Ａｌ：６．４％、Ｚｎ：１．０％、Ｍｎ：０．２８％を含み、残部がＭｇおよび不純物
ＡＺ９１：Ａｌ：９．０％、Ｚｎ：０．７％、Ｍｎ：０．１％を含み、残部がＭｇおよび不純物
ＺＫ６０：Ｚｎ：５．５％、Ｚｒ：０．４５％を含み、残部がＭｇおよび不純物
【００８７】
これら押出材を用いて、１００℃の加工温度にて、１５〜２５％／ｐａｓｓの加工度でφ１．２ｍｍまで穴ダイスにより線引き加工を実施した。加工温度は、穴ダイス前に設置したヒータの加熱温度とした。加工温度への昇温速度は１〜１０℃／ｓｅｃ、引き抜き加工の線速は５ｍ／ｍｉｎである。また、冷却は衝風冷却にて行った。冷却速度は０．１℃／ｓｅｃ以上である。引き抜き加工時、本発明材は断線することもなく、長尺のワイヤを得ることができた。得られたワイヤは、直径の１０００倍以上の長さを有していた。
【００８８】
さらに引張試験、偏径差および表面粗さの測定を行った。偏径差は、ワイヤの同一断面における径の最大値と最小値との差である。表面粗さはＲｚにより評価した。各試験結果を表１０に示す。比較材として押出材の各特性も示した。
【００８９】
【表１０】

【００９０】
表１０に示すように、本発明材は引張強度が３００ＭＰａ以上かつ絞りが１５％以上、伸びが６％以上、更には、偏径差が０．０１ｍｍ以下、表面粗さＲｚ≦１０μｍの特徴を有することがわかる。
【００９１】
（実施例８）
更に、引き抜き加工温度５０℃、１５０℃、２００℃のそれぞれで、線径φ０．８、φ１．６、φ２．４ｍｍの溶接用ワイヤを実施例７と同様に作製し、同様の評価を行った。その結果、いずれも引張強度が３００ＭＰａ以上かつ絞りが１５％以上、伸びが６％以上、更には、偏径差が０．０１ｍｍ以下、表面粗さＲｚ≦１０μｍの特徴を有することが確認された。
【００９２】
また、得られたワイヤを１．０〜５．０ｋｇ毎にリールに整列巻きをした。リールから引出されたワイヤは良好な線癖を有し、手溶接、ＭＩＧ、ＴＩＧ等の自動溶接で良好な溶接が期待できる。
【００９３】
（実施例９）
ＡＺ−３１合金の押出材（φ８．０ｍｍ）を用いて、加工温度１００℃にてφ４．６ｍｍまで引き抜き加工を行い（１パス加工度１０％以上、トータル加工度６７％）ワイヤを得た。加工温度は、穴ダイス前に設置したヒータの加熱温度とした。加工温度への昇温速度は１〜１０℃／ｓｅｃ、引き抜き加工の線速は２〜１０ｍ／ｍｉｎである。引き抜き加工後の冷却は衝風冷却にて行い、冷却速度は０．１℃／ｓｅｃ以上である。得られたワイヤに１００℃〜３５０℃にて１５ｍｉｎの熱処理を行った。その引張特性を表１１に示す。ここでは、組織が混粒組織であったもの又は平均結晶粒径が５μｍ以下であったものを「本発明例」と表示した。
【００９４】
【表１１】

【００９５】
表１１をみると、熱処理温度が８０℃以下では強度が高いものの伸び、絞りが低く、靭性に乏しい。この際の結晶組織は加工組織であり、加工前の粒径を反映して平均粒径は２０μｍ程度である。
【００９６】
また、加熱温度が１５０℃以上になると、若干強度低下するものの、伸び、絞りの回復が著しく、強度、靭性にバランスのとれたワイヤが得られる。この際の結晶組織は、１５０℃および２００℃の加熱温度では、平均粒径３μｍ以下の結晶粒と同１５μｍ以上の結晶粒の混粒組織となっている。２５０℃以上では、結晶粒の大きさがほぼ均一な組織を呈しており、その平均粒径は表１１に記載の通りである。平均粒径が５μｍ以下では、強度３００ＭＰａ以上の確保が可能である。
【００９７】
（実施例１０）
ＡＺ−３１合金の押出材（φ８．０ｍｍ）を用いて、加工温度を１５０℃とし、１パス加工度１０％以上でトータル加工度を変化させて引き抜き加工を行い、得られた線材に２００℃で１５分熱処理して、熱処理後の材料の引張特性を評価した。引き抜き加工の加工温度は、穴ダイス前に設置したヒータの加熱温度とした。加工温度への昇温速度は２〜５℃／ｓｅｃ、引き抜き加工の線速は２〜５ｍ／ｍｉｎである。引き抜き加工後の冷却は衝風冷却にて行い、冷却速度は０．１℃／ｓｅｃ以上とした。その結果を表１２に示す。ここでは、組織が混粒組織であったものを「本発明例」と表示した。
【００９８】
【表１２】

【００９９】
表１２を見てわかるように、トータル加工度１０％以下では、組織制御が不十分であるが、同１５％以上では、平均粒径３μｍ以下の結晶粒と同１５μｍ以上の結晶粒の混合組織となっており、高強度と高靭性が両立している。
【０１００】
図１に加工度を２３％とした熱処理後のワイヤの光学顕微鏡による組織写真を示す。この写真から明らかなように、平均粒径３μｍ以下の結晶粒と同１５μｍ以上の結晶粒の混合組織となっていることがわかり、３μｍ以下の結晶粒の面積率は約１５％である。本実施例で混粒組織が見られたものは、３μｍ以下の結晶粒の面積率がいずれも１０％以上であった。また、トータル加工度３０％以上では、より一層強度も高くなり効果的である。
（実施例１１）
ＺＫ６０合金の押出材（φ６．０ｍｍ）を用いて、加工温度１５０℃にてφ５．０ｍｍまで引き抜き加工を行った（トータル加工度３０．６％）。加工温度は、穴ダイス前に設置したヒータの加熱温度とした。加工温度への昇温速度は２〜５℃／ｓｅｃ、引き抜き加工の線速は２ｍ／ｍｉｎである。引き抜き加工後の冷却は衝風冷却にて行い、冷却速度は０．１℃／ｓｅｃ以上とした。冷却後のワイヤに１００℃〜３５０℃にて１５ｍｉｎの熱処理を行った。熱処理後の線材の引張特性を表１３に示す。ここでは、組織が混粒組織であったもの又は平均結晶粒径が５μｍ以下であったものを「本発明例」と表示した。
【０１０１】
【表１３】

【０１０２】
表１３をみると加熱温度８０℃以下では、強度は高いものの伸び、絞りが低く、靭性に乏しい。この際の結晶組織は、加工組織であり、加工前の粒径を反映して粒径は１０数μｍである。
【０１０３】
また、加熱温度が１５０℃以上になると、若干強度低下するものの、伸び、絞りの回復が著しく、強度、靭性にバランスのとれたワイヤが得られる。この際の結晶組織は、１５０℃および２００℃の加熱温度では、平均粒径３μｍ以下の結晶粒と同１５μｍ以上の結晶粒の混粒組織となっている。２５０℃以上では均一な粒径の組織を呈しており、粒径は表１３に記載の通りである。平均粒径が５μｍ以下では、強度３９０ＭＰａ以上の確保が可能である。
【０１０４】
（実施例１２）
ＡＺ３１合金、ＡＺ６１合金、ＺＫ６０合金の押出材（φ５．０ｍｍ）を用いて、φ４．３ｍｍまで穴ダイスによる温間引き抜き加工を行った。加工温度は、穴ダイス前に設置したヒータの加熱温度とした。加工温度への昇温速度は２〜５℃／ｓｅｃ、引き抜き加工の線速は３ｍ／ｍｉｎである。引き抜き加工後の冷却は衝風冷却にて行い、冷却速度は０．１℃／ｓｅｃ以上とした。引き抜き加工の際の加熱温度と得られたワイヤの特性を表１４〜表１６に示す。ワイヤの特性はＹＰ比および捻り降伏比τ_０．２／τ_ｍａｘを評価した。ＹＰ比は０．２％耐力／引張強度である。捻り降伏比は、捻り試験における０．２％耐力τ_０．２の最大せん断応力τ_ｍａｘに対する比である。捻り試験は、チャック間距離を１００ｄ（ｄ：線の直径）とし、試験の際に求められるトルクと回転角の関係からτ_０．２及びτ_ｍａｘを求めた。比較材として、押出材の特性も合わせて示す。
【０１０５】
【表１４】

【０１０６】
【表１５】

【０１０７】
【表１６】

【０１０８】
表１４〜１６をみると、押出材のＹＰ比は、０．７程度であるのに対し、本発明例ではいずれも０．９以上となっており、０．２％耐力の値は、引張強度の上昇以上に増加している。これにより、構造材として有効な特性が得られることがわかる。
【０１０９】
また、τ_０．２／τ_ｍａｘ比は、押出材ではいずれの組成においても０．５未満であるが、本発明例では０．６以上の高い値を示すことがわかる。この結果は、横断面が異形（非円形）である線、棒材についても同じである。
【０１１０】
（実施例１３）
ＡＺ３１合金、ＡＺ６１合金、ＺＫ６０合金の押出材（φ５．０ｍｍ）を用いて、φ４．３ｍｍまで穴ダイスによる線引き加工を５０℃の温度で行った。加工温度は、穴ダイス前に設置したヒータの加熱温度とした。加工温度への昇温速度は５〜１０℃／ｓｅｃ、引き抜き加工の線速は３ｍ／ｍｉｎである。引き抜き加工後の冷却は衝風冷却にて行い、冷却速度は０．１℃／ｓｅｃ以上とした。冷却後のワイヤに１００〜３００℃×１５ｍｉｎの熱処理を行い、ワイヤの特性として実施例１２と同様にＹＰ比および捻り降伏比τ_０．２／τ_ｍａｘを評価した。その結果を、表１７〜表１９に示す。比較材として、押出材の特性も合わせて示す。
【０１１１】
【表１７】

【０１１２】
【表１８】

【０１１３】
【表１９】

【０１１４】
表１７〜１９をみると、押出材のＹＰ比は０．７程度であるのに対し、線引きと熱処理を施した本発明例のＹＰ比は０．７５以上である。その中で、ＹＰ比を０．７５以上０．９０未満に制御した本発明例では、伸び値が大きく加工性が良好であることがわかる。より大きい強度を追求すると、ＹＰ比は０．８０以上、０．９０未満のものが伸びとのバランスも良好でなお好ましい。
【０１１５】
また、捻り降伏比τ_０．２／τ_ｍａｘは、押出材ではいずれの組成においても０．５未満であるが、線引きと熱処理を施した場合では０．５０以上の高い値を示す。加工性を考え、伸び値を確保しようとした場合、τ_０．２／τ_ｍａｘ比は０．５０以上０．６０未満が好ましいことがわかる。
【０１１６】
これらの結果は、組成に関わらず同じ傾向を示している。また、最適な熱処理条件は、線引き加工度、加熱時間との影響を受け、線引き条件によって異なる。さらに、この結果は、横断面が異形（非円形）である線、棒材についても同じである。
【０１１７】
（実施例１４）
質量％で、Ａｌ：１．２％、Ｚｎ：０．４％、Ｍｎ：０．３％を含み、残部がＭｇおよび不純物からなるマグネシウム合金ＡＺ１０合金の押出材（φ５．０ｍｍ）を用いて、加工温度１００℃にてφ４．０ｍｍまでトータル断面減少率３６％（２パス）の引き抜き加工を行った。この引き抜き加工には穴ダイスを用いた。また、加工温度は、穴ダイスの前にヒータを設置して、ヒータの加熱温度を加工温度としている。加工温度への昇温速度は１０℃／ｓｅｃ、冷却速度は０．１℃／ｓｅｃ以上、引き抜き加工の線速は２ｍ／ｍｉｎである。また、引き抜き加工後の冷却は衝風冷却にて行った。その後、得られた線状体に５０℃から３５０℃の温度にて２０分の熱処理を行い、種々のワイヤを得た。
【０１１８】
そのワイヤの引張強度、破断伸び、絞り、ＹＰ比、τ_０．２／τ_ｍａｘ、結晶粒径を調査した。平均結晶粒径は、ワイヤの断面組織を顕微鏡にて拡大し、視野内における複数の結晶の粒径を測定して、その平均値を求めた。結果を表２０に示す。φ５．０ｍｍの押出材の引張強度は２２５ＭＰａ、靭性は、絞り３８％、伸び９％、ＹＰ比は０．６４、τ_０．２／τ_ｍａｘ比は０．５５である。
【０１１９】
【表２０】

【０１２０】
表２０から明らかなように、押出材に比べると、引き抜き加工したワイヤは強度が大幅に向上している。加熱処理後の機械的特性をみると１００℃以下の加熱温度では線引き後の特性と大きな変化はない。１５０℃以上の温度では、破断伸び、絞りとも大きく上昇していることがわかる。熱処理を行わず引き抜き加工したままのワイヤと比較すると引張強度、ＹＰ比、τ_０．２／τ_ｍａｘ比は低下するものの、元の押出材の引張強度、ＹＰ比、τ_０．２／τ_ｍａｘ比を大きく上回っている。加熱処理温度が３００℃を越えると引張強度、ＹＰ比、τ_０．２／τ_ｍａｘ比の上昇分が小さくなり、好ましくは３００℃以下の加熱処理温度が望まれる。
【０１２１】
ここで得られたワイヤの結晶粒径は、表２０に示すように１５０℃以上の加熱温度では１０μｍ以下、２００〜２５０℃では５μｍ以下の微細な結晶粒となっていることがわかる。また、１５０℃の温度では、３μｍ以下の結晶粒と１５μｍ以上の結晶粒の混粒組織となっており、３μｍ以下の結晶粒の面積率が１０％以上であった。
【０１２２】
さらに、得られたワイヤは、長さが直径の１０００倍以上であり、表面粗さＲｚは１０μｍ以下であった。また、ワイヤ表面の軸方向残留引張応力をＸ線回折法により求めたところ、同応力は８０ＭＰａ以下であった。さらに、偏径差は０．０１ｍｍ以下であった。偏径差は、ワイヤの同一断面における径の最大値と最小値との差である。
【０１２３】
そして、得られたワイヤ（φ４．０ｍｍ）を用い、室温にてバネ外径３５ｍｍのばね加工を行ったところ、本発明ワイヤは問題なくばね加工可能であった。
【０１２４】
（実施例１５）
質量％で、Ａｌ：１．２％、Ｚｎ：０．４％、Ｍｎ：０．３％を含み、残部がＭｇおよび不純物からなるマグネシウム基合金ＡＺ１０合金の押出材（φ５．０ｍｍ）を用いて、種々の条件で引き抜き加工を行い、種々のワイヤを得た。この引き抜き加工には穴ダイスを用いた。また、加工温度は、穴ダイスの前にヒータを設置して、ヒータの加熱温度を加工温度としている。加工温度への昇温速度は１０℃／ｓｅｃ、引き抜き加工の線速は２ｍ／ｍｉｎである。得られたワイヤの特性を表２１および表２２に示す。表２１は断面減少率が一定で加工温度を変えた場合、表２２は加工温度が一定で断面減少率を変えた場合の条件と結果である。本例では、１パスのみの加工であり、ここでの「断面減少率」はトータル断面減少率である。
【０１２５】
【表２１】

【０１２６】
【表２２】

【０１２７】
表２１をみると押出材の引張強度は２０５ＭＰａ、靭性は絞り３８％、伸び９％である。一方で、５０℃以上の温度で引き抜き加工を行ったＮｏ．１−３〜１−９では、３０％以上の絞り値と６％以上の伸び値を有している。さらに、これらの試験材は２５０ＭＰａ以上の高い引張強度、０．９０以上のＹＰ比、０．６０以上のτ_０．２／τ_ｍａｘ比を有しており、靭性を大きく低下させることなく、強度を向上できていることがわかる。中でも、１００℃以上の温度で引き抜き加工を行ったＮｏ．１−４〜１−９は、４０％以上の絞り値と１０％以上の伸び値を有しており、靭性の点で特に優れている。これに対して、引き抜き加工温度が３００℃を超えると強度の上昇率は小さく、２０℃の室温で引き抜き加工を行ったＮｏ．１−２は、断線のため加工できなかった。従って、５０℃から３００℃（好ましくは１００℃から３００℃）の加工温度で、より優れた強度−靭性バランスを示す。
【０１２８】
表２２をみると、加工度が５％のＮｏ．２−２では、引張強度、ＹＰ比、τ_０．２／τ_ｍａｘ比の上昇率は小さく、１０％以上の加工度になると引張強度、ＹＰ比、τ_０．２／τ_ｍａｘ比の上昇率は大きくなっている。また、加工度が３５％のＮｏ．２−６では引き抜き加工はできなかった。このことから加工度１０％以上３０％以下の引き抜き加工によって靭性を低下させることなく、２５０ＭＰａ以上の高い引張強度、０．９以上のＹＰ比、０．６０以上のτ_０．２／τ_ｍａｘ比の優れた特性を示すことがわかる。
【０１２９】
表２１、表２２のいずれにおいても得られたワイヤは、長さが直径の１０００倍以上であり、多パスの繰り返し引き抜き加工も可能であった。また、表面粗さＲｚは１０μｍ以下であった。ワイヤ表面の軸方向残留引張応力もＸ線回折法により求めたところ、同応力は８０ＭＰａ以下であった。さらに、偏径差は０．０１ｍｍ以下であった。この偏径差は、ワイヤの同一断面における径の最大値と最小値との差である。
【０１３０】
そして、得られたワイヤを用い、室温にてバネ外径４０ｍｍのばね加工を行ったところ、本発明ワイヤは問題なくばね加工可能であった。
【０１３１】
（実施例１６）
質量％で、Ａｌ：４．２％、Ｍｎ：０．５０％、Ｓｉ：１．１％を含み、残部がＭｇと不純物からなるマグネシウム合金（ＡＳ４１）およびＡｌ：６．１％、Ｍｎ：０．４４％を含み、残部がＭｇと不純物からなるマグネシウム合金（ＡＭ６０）の押出材（φ５．０ｍｍ）を用いて、φ４．５ｍｍまで断面減少率１９％の穴ダイスによる加工を行った。その際の加工条件と得られたワイヤの特性を表２３に示す。
【０１３２】
【表２３】

【０１３３】
表２３をみると、ＡＳ４１合金の押出材の引張強度は２５９ＭＰａ、０．２％耐力は１５１ＭＰａであり、ＹＰ比は０．５８と低い。また、絞り１９．５％、伸び９．５％である。
【０１３４】
ＡＭ６０合金の押出材の引張強度も２６５ＭＰａ、０．２％耐力は１６０ＭＰａであり、ＹＰ比は０．６０と低い。
【０１３５】
一方で、１５０℃の温度に加熱し、引き抜き加工を行ったものは、ＡＳ４１合金、ＡＭ６０合金共に、３０％以上の絞り値と６％以上の伸び値を有しており、３００ＭＰａ以上の高い引張強度および０．９以上のＹＰ比を有しており、靭性を大きく低下させることなく、強度を向上させることができることがわかる。また、２０℃の室温での引き抜き加工は、断線のため加工できなかった。
【０１３６】
（実施例１７）
質量％で、Ａｌ：４．２％、Ｍｎ：０．５０％、Ｓｉ：１．１％を含み、残部がＭｇと不純物からなるマグネシウム合金（ＡＳ４１）およびＡｌ：６．１％、Ｍｎ：０．４４％を含み、残部がＭｇと不純物からなるマグネシウム合金（ＡＭ６０）の押出材（φ５．０ｍｍ）を用いて、１５０℃の加工温度にてφ４．５ｍｍまで断面減少率１９％の穴ダイスによる加工を行った。この加工後の冷却速度は１０℃／ｓｅｃである。その際に得られたワイヤを８０℃および２００℃にて１５分間加熱し、室温にて引張特性、結晶粒径の評価を行った。その結果を表２４に示す。
【０１３７】
【表２４】

【０１３８】
線引き加工後は、引張強度、０．２％耐力、ＹＰ比が大幅に向上している。線引き後の熱処理材の機械的特性をみると、８０℃の加工温度では線引き後の特性と大きな変化はない。２００℃の温度では、破断伸び、絞りとも大きく上昇していることがわかる。線引きのままの材料と比較すると、引張強度、０．２％耐力、ＹＰ比は低下するものの、元の押出材の引張強度、０．２％耐力、ＹＰ比を大きく上回っている。
【０１３９】
この際に得られた結晶粒径は、表２４に示すように２００℃の加熱温度では５μｍ以下の微細な結晶粒となっている。また、得られたワイヤは長さが直径の１０００倍以上であり、表面粗さＲｚは１０μｍ以下、軸方向残留引張応力は８０ＭＰａ以下、偏径差は０．０１ｍｍ以下であった。
【０１４０】
また、得られたワイヤ（φ４．５ｍｍ）を用い、室温にてバネ外径４０ｍｍのばね加工を行ったところ、本発明ワイヤは問題なくばね加工可能であった。
【０１４１】
（実施例１８）
質量％で、Ｚｎ：２．５％、Ｚｒ：０．６％、ＲＥ：２．９％を含み、残部がＭｇと不純物からなるマグネシウム合金（ＥＺ３３）の鋳造材を熱間鍛造によりφ５．０ｍｍの棒材とし、φ４．５ｍｍまで断面減少率１９％の穴ダイスによる加工を行った。その際の加工条件と得られたワイヤの特性を表２５に示す。なお、ＲＥにはジジムを使用している。
【０１４２】
【表２５】

【０１４３】
表２５をみると、ＥＺ３３合金の押出材の引張強度は１８０ＭＰａ、０．２％耐力は１２１ＭＰａであり、ＹＰ比は０．６７と低い。また、絞りは１５．２％、伸びは４．０％である。
【０１４４】
一方で、１５０℃の温度に加熱し、引き抜き加工を行ったものは、３０％以上の絞り値と６％以上の伸び値を有しており、２２０ＭＰａ以上の高い引張強度および０．９以上のＹＰ比を有しており、靭性を大きく低下させることなく、強度を向上させることができることがわかる。また、２０℃の室温での引き抜き加工は、断線のため加工できなかった。
【０１４５】
（実施例１９）
質量％で、Ｚｎ：２．５％、Ｚｒ：０．６％、ＲＥ：２．９％を含み、残部がＭｇと不純物からなるマグネシウム合金（ＥＺ３３）の鋳造材を熱間鍛造によりφ５．０ｍｍの棒材とし、φ４．５ｍｍまで断面減少率１９％の穴ダイスによる加工を行った。この加工後の冷却速度は１０℃／ｓｅｃである。その際に得られたワイヤを８０℃および２００℃にて１５分間加熱し、室温にて引張特性、結晶粒径の評価を行った。その結果を表２６に示す。なお、ＲＥにはジジムを使用している。
【０１４６】
【表２６】

【０１４７】
線引き加工後は、引張強度、０．２％耐力、ＹＰ比が大幅に向上している。線引き後の熱処理材の機械的特性をみると、８０℃の加工温度では線引き後の特性と大きな変化はない。２００℃の温度では、破断伸び、絞りとも大きく上昇していることがわかる。線引きのままの材料と比較すると、引張強度、０．２％耐力、ＹＰ比は低下するものの、元の押出材の引張強度、０．２％耐力、ＹＰ比を大きく上回っている。
【０１４８】
この際に得られた結晶粒径は、表２６に示すように２００℃の加熱温度では５μｍ以下の微細な結晶粒となっている。また、得られたワイヤは、長さが直径の１０００倍以上であり、表面粗さＲｚは、１０μｍ以下、軸方向残留引張応力は８０ＭＰａ以下、偏径差は０．０１ｍｍ以下であった。
【０１４９】
（実施例２０）
質量％で、Ａｌ：１．９％、Ｍｎ：０．４５％、Ｓｉ：１．０％を含み、残部がＭｇと不純物からなるマグネシウム合金（ＡＳ２１）の押出材（φ５．０ｍｍ）を用いて、φ４．５ｍｍまで断面減少率１９％の穴ダイスによる加工を行った。その際の加工条件と得られたワイヤの特性を表２７に示す。
【０１５０】
【表２７】

【０１５１】
表２７をみると、ＡＳ２１合金の押出材の引張強度は２１５ＭＰａ、０．２％耐力は１４１ＭＰａであり、ＹＰ比は０．６６と低い。
【０１５２】
一方で、１５０℃の温度に加熱し、引き抜き加工を行ったものは、４０％以上の絞り値と６％以上の伸び値を有しており、２５０ＭＰａ以上の高い引張強度および０．９以上のＹＰ比を有しており、靭性を大きく低下させることなく、強度を向上させることができることがわかる。また、２０℃の室温での引き抜き加工は、断線のため加工できなかった。
【０１５３】
また、得られたワイヤは、長さが直径の１０００倍以上であり、表面粗さＲｚは、１０μｍ以下、軸方向残留引張応力は８０ＭＰａ以下、偏径差は０．０１ｍｍ以下であった。更に、得られたワイヤ（φ４．５ｍｍ）を用い、室温にてバネ外径４０ｍｍのばね加工を行ったところ、本発明ワイヤは問題なくばね加工可能であった。
【０１５４】
（実施例２１）
質量％で、Ａｌ：１．９％、Ｍｎ：０．４５％、Ｓｉ：１．０％を含み、残部がＭｇと不純物からなるマグネシウム合金（ＡＳ２１）の押出材（φ５．０）を用いて、１５０℃の加工温度にてφ４．５ｍｍまで断面減少率１９％の穴ダイスによる加工を行った。この加工後の冷却速度は１０℃／ｓｅｃである。その際に得られたワイヤを、８０℃および２００℃にて１５分間加熱し、室温にて引張特性、結晶粒径の評価を行った。その結果を表２８に示す。
【０１５５】
【表２８】

【０１５６】
線引き加工後は、引張強度、０．２％耐力、ＹＰ比が大幅に向上している。線引き後の熱処理材の機械的特性をみると、８０℃の加工温度では線引き後の特性と大きな変化はない。２００℃の温度では、破断伸び、絞りとも大きく上昇していることがわかる。線引きのままの材料と比較すると、引張強度、０．２％耐力、ＹＰ比は低下するものの、元の押出材の引張強度、０．２％耐力、ＹＰ比を大きく上回っている。
【０１５７】
この際、得られた結晶粒径は、表２８に示すように２００℃の加熱温度では５μｍ以下の微細な結晶粒となっている。また、得られたワイヤは長さが直径の１０００倍以上であり、表面粗さＲｚは１０μｍ以下、軸方向残留引張応力は８０ＭＰａ以下、偏径差は０．０１ｍｍ以下であった。
【０１５８】
また、得られたワイヤ（φ４．５ｍｍ）を用い、室温にてバネ外径４０ｍｍのばね加工を行ったところ、本発明ワイヤは問題なくばね加工可能であった。
【０１５９】
（実施例２２）
ＡＺ３１合金の押出材（φ５．０ｍｍ）を準備し、加工温度１００℃にてφ４．０ｍｍまで減面率３６％（２パス）の引き抜き加工を行った。引き抜き加工後の冷却速度は１０℃／ｓｅｃである。その後、１００℃から３５０℃の温度にて６０分の加熱処理を行い、種々のワイヤを得た。そして、そのワイヤの回転曲げ疲労強度を中村式回転曲げ疲労試験にて評価した。疲労試験は１０^７回にて実施した。また、各試料の平均結晶粒径、軸方向残留引張応力も同時に評価を行った。その結果を表２９に示す。
【０１６０】
【表２９】

【０１６１】
表２９から明らかなように、１５０℃以上、２５０℃以下の熱処理により、疲労強度は１０５ＭＰａ以上と最大となる。その際、平均結晶粒径は４μｍ以下、軸方向残留引張応力は１０ＭＰａ以下となっている。
【０１６２】
また、ＡＺ６１合金、ＡＳ４１合金、ＡＭ６０合金およびＺＫ６０合金の押出材（φ５．０ｍｍ）を準備し、同様の評価を行った。その結果を表３０〜表３３に示す。
【０１６３】
【表３０】

【０１６４】
【表３１】

【０１６５】
【表３２】

【０１６６】
【表３３】

【０１６７】
いずれの合金系でも、引き抜き加工とその後の熱処理との組み合わせにより１０５ＭＰａ以上の疲労強度が得られ、１５０℃以上、２５０℃以下の熱処理により、疲労強度は最大となる。また、平均結晶粒径は４μｍ以下、軸方向残留引張応力は１０ＭＰａ以下となっている。
【０１６８】
【発明の効果】
以上説明したように、本発明ワイヤの製造方法によれば、従来困難であったマグネシウム合金の引き抜き加工が可能になり、強度と靭性に優れたマグネシウム基合金ワイヤを得ることができる。
【０１６９】
また、本発明のマグネシウム基合金ワイヤは、高靭性で、ばね加工をはじめとする後加工が容易であり、靭性および比強度に優れる軽量材料として有効である。従って、ＭＤプレーヤー、ＣＤプレーヤー、携帯電話等のフレームの補強用やスーツケースのフレームに使用されるワイヤ、その他軽量ばね、さらには自動溶接機等で使用可能な長尺の溶接線、ねじ等への有効利用が期待される。その他、構造材としても利用することが期待される。
【図面の簡単な説明】
【図１】本発明ワイヤの光学顕微鏡による組織写真である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high-toughness magnesium-based alloy wire and a method for manufacturing the same. Further, the present invention relates to a spring using a magnesium-based alloy wire.
[0002]
[Prior art]
Magnesium-based alloys are lighter than aluminum, have higher specific strength and specific rigidity than steel and aluminum, and are widely used for bodies of various electric products in addition to aircraft parts and automobile parts.
[0003]
[Problems to be solved by the invention]
However, Mg and its alloys have poor ductility due to their close-packed hexagonal lattice structure, and are extremely poor in plastic workability. Therefore, it has been extremely difficult to obtain wires of Mg and its alloys.
[0004]
Further, although a round bar was obtained by hot rolling or hot extrusion of a cast material, it had no toughness and a drawing value of less than 15%, and was not suitable for, for example, cold spring processing. Further, when a magnesium-based alloy is applied to a structural material, the YP ratio (0.2% proof stress / tensile strength) and the torsional yield ratio τ are compared with those of a general structural material. _0.2 / Τ _max (0.2% proof stress τ in torsion test _0.2 Maximum shear stress τ _max Is lower.
[0005]
On the other hand, JP-A-7-3375 discloses a high-strength magnesium-based alloy of Mg-Zn-X type (X: Y, Ce, Nd, Pr, Sm, Mm), and has a strength of 600 MPa to 726 MPa. It has gained. As for toughness, a close bending test has been conducted.
[0006]
However, the material shape obtained here is only a short bar having a diameter of 6 mm and a length of 270 mm, and a long wire cannot be obtained by the described method (powder extrusion). Further, since additional elements such as Y, La, Ce, Nd, Pr, Sm, and Mm are included in the order of several atomic%, not only is the cost high, but also the recyclability is poor.
[0007]
Furthermore, Journal of materials science letters 20, 20, 457-449 describes the fatigue strength of a cast material of AZ91 alloy, which is as low as about 20 MPa. The JSME 72nd Annual Conference Performance Papers I, P35-P37 describe the results of a rotary bending fatigue test of an AZ21 alloy extruded material. ⁷ Although it is not the evaluation up to the number of times, it indicates that the fatigue strength is 100 MPa. In the 99th Fall Meeting of the Japan Institute of Light Metals (2000) P73 to P74, the rotational bending fatigue characteristics of a molded material by thixomolding of AE40, AM60 and ACaSr6350p are described. However, the fatigue strength at room temperature is 65 MPa, 90 MPa, and 100 MPa, respectively. That is, the fatigue strength exceeding 100 MPa has not been obtained in the rotating bending fatigue strength of the magnesium-based alloy.
[0008]
Accordingly, it is a primary object of the present invention to provide a magnesium-based alloy wire having excellent strength and toughness, a method of manufacturing the same, and a spring using the magnesium-based alloy wire.
[0009]
Another object of the present invention is to provide a YP ratio or τ _0.2 / Τ _max To provide a magnesium-based alloy wire having a high density and a method of manufacturing the same.
[0010]
Still another object of the present invention is to provide a magnesium-based alloy wire having a high fatigue strength exceeding 100 MPa and a method for producing the same.
[0011]
[Means for Solving the Problems]
The present inventors have conducted various studies on the drawing of magnesium-based alloys, which are usually difficult, and as a result, specified the processing temperature during the drawing, and further combined with a predetermined heat treatment as necessary to obtain strength and strength. They have found that a wire having excellent toughness can be obtained, and have completed the present invention.
[0012]
(Magnesium-based alloy wire)
That is, the first feature of the magnesium-based alloy wire of the present invention is a magnesium-based alloy wire having any one of the following chemical components (A) to (E), and has a diameter d of 0.1 mm or more and 10.0 mm: Hereinafter, the length L is 1000 d or more, the tensile strength is 220 MPa or more, the drawing is 15% or more, and the elongation is 6% or more.
[0013]
(A) Magnesium-based alloy containing Al: 2.0 to 12.0% and Mn: 0.1 to 1.0% by mass%
(B) In mass%, Al: 2.0 to 12.0%, Mn: 0.1 to 1.0%, Zn: 0.5 to 2.0%, Si: 0.3 to 2 Magnesium-based alloy containing at least one element selected from 0.0%
(C) Magnesium-based alloy containing Zn: 1.0 to 10.0% and Zr: 0.4 to 2.0% by mass%
(D) Magnesium base alloy containing, by mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, and further containing Mn: 0.5 to 2.0%
(E) Magnesium-based alloy containing Zn: 1.0 to 10.0% and rare earth element: 1.0 to 3.0% by mass%
[0014]
As the magnesium-based alloy used for this wire, any of a magnesium-based alloy for casting and a magnesium-based alloy for wrought can be used. More specifically, for example, the AM system, the AZ system, the AS system, the ZK system, and the EZ system in the ASTM symbol can be used. In general, it is used as an alloy containing Mg and impurities in addition to the above chemical components. The impurities include Fe, Si, Cu, Ni, Ca and the like.
[0015]
AM60 in the AM system includes Al: 5.5 to 6.5%, Zn: 0.22% or less, Cu: 0.35% or less, Mn: 0.13% or more, Ni: 0.03% or less, Si: It is a magnesium-based alloy containing 0.5% or less. AM100 has Al: 9.3 to 10.7%, Zn: 0.3% or less, Cu: 0.1% or less, Mn: 0.1 to 0.35%, Ni: 0.01% or less, Si: It is a magnesium-based alloy containing 0.3% or less.
[0016]
AZ10 in the AZ system is, by mass%, Al: 1.0 to 1.5%, Zn: 0.2 to 0.6%, Mn: 0.2% or more, Cu: 0.1% or less, Si: 0. It is a magnesium-based alloy containing 1% or less and Ca: 0.4% or less. AZ21 is in mass% Al: 1.4 to 2.6%, Zn: 0.5 to 1.5%, Mn: 0.15 to 0.35%, Ni: 0.03% or less, and Si: 0. It is a magnesium-based alloy containing 1% or less. AZ31: Al: 2.5 to 3.5%, Zn: 0.5 to 1.5%, Mn: 0.15% to 0.5%, Cu: 0.05% or less, Si: 0.1% Hereinafter, it is a magnesium-based alloy containing 0.04% or less of Ca. AZ61: Al: 5.5 to 7.2%, Zn: 0.4 to 1.5%, Mn: 0.15 to 0.35%, Ni: 0.05% or less, Si: 0.1% or less Is a magnesium-based alloy. AZ91 is Al: 8.1 to 9.7%, Zn: 0.35 to 1.0%, Mn: 0.13% or more, Cu: 0.1% or less, Ni: 0.03% or less, Si: It is a magnesium-based alloy containing 0.5% or less.
[0017]
AS21 in the AS system is, by mass%, Al: 1.4 to 2.6%, Zn: 0.1% or less, Cu: 0.15% or less, Mn: 0.35 to 0.60%, Ni: 0 It is a magnesium-based alloy containing 0.001% and Si: 0.6 to 1.4%. AS41: Al: 3.7 to 4.8%, Zn: 0.1% or less, Cu: 0.15% or less, Mn: 0.35 to 0.60%, Ni: 0.001% or less, Si: It is a magnesium-based alloy containing 0.6 to 1.4%.
[0018]
ZK60 in the ZK system is a magnesium-based alloy containing 4.8 to 6.2% of Zn and 0.4% or more of Zr.
[0019]
EZ33 in the EZ system is Zn: 2.0 to 3.1%, Cu: 0.1% or less, Ni: 0.01% or less, RE: 2.5 to 4.0%, Zr: 0.5 to 1 % Based magnesium alloy. Here, RE is a rare earth element, and usually a mixture of Pr and Nd is often used.
[0020]
Although it is difficult to obtain sufficient strength with magnesium alone, preferable strength can be obtained by including the above-mentioned chemical components. Further, a wire having excellent toughness can be obtained by a manufacturing method described later.
[0021]
By providing the above-mentioned tensile strength, drawing, and elongation, it has both strength and toughness, and can easily perform post-processing such as spring processing. The more preferable tensile strength is 250 MPa or more, more preferably 300 MPa or more, particularly preferably 330 MPa or more in AM, AZ, AS and ZK systems. More preferred tensile strength in the EZ system is 250 MPa or more.
[0022]
Further, a more preferable aperture is 30% or more, particularly preferably 40% or more. Among them, AZ31 is a suitable chemical component for achieving a reduction of 40% or more. Further, a magnesium-based alloy containing Al: less than 0.1 to 2.0% and Mn: 0.1 to 1.0% is also a preferable chemical component for achieving a reduction of 30% or more. The more preferable reduction of the magnesium-based alloy containing Al: less than 0.1 to 2.0% and Mn: 0.1 to 1.0% is 40% or more, and the particularly preferable reduction is 45% or more. And more preferable elongation is 10% or more, and tensile strength is 280 MPa or more.
[0023]
A second feature of the magnesium-based alloy wire of the present invention is the magnesium-based alloy wire having the above-mentioned chemical component, and has a YP ratio of 0.75 or more.
[0024]
The YP ratio is a ratio represented by “0.2% proof stress / tensile strength”. When a magnesium-based alloy is applied as a structural material, it is desired to have high strength. At that time, since the actual use limit is determined not by the tensile strength but by the magnitude of the 0.2% proof stress, in order to obtain a high-strength magnesium-based alloy, not only increase the absolute value of the tensile strength but also , YP ratio needs to be increased. Conventionally, in the case of wrought materials such as AZ10 alloy and AZ21 alloy, a round bar is obtained by hot extrusion, but the tensile strength is 200 to 240 MPa, and the YP ratio (0.2% proof stress / tensile strength) Is less than 0.5 to less than 0.75. In the present invention, a magnesium-based alloy having a YP ratio of 0.75 or more can be obtained by specifying a processing temperature, a rate of temperature rise to the processing temperature, a degree of processing, and a linear speed during drawing, or by performing a predetermined heat treatment after drawing. A wire can be obtained.
[0025]
For example, the rate of temperature rise to the processing temperature: 1 ° C./sec to 100 ° C./sec, the processing temperature: 50 ° C. or more and 200 ° C. or less (more preferably 150 ° C. or less), the workability: 10% or more, and the linear velocity: 1 m / By performing the drawing process in seconds or more, a magnesium-based alloy wire having a YP ratio of 0.90 or more can be obtained. Furthermore, by cooling after the drawing process, and performing a heat treatment at a temperature of 150 ° C. or more and 300 ° C. or less and a holding time of 5 minutes or more, a magnesium-based alloy wire having a YP ratio of 0.75 or more and less than 0.90 can be obtained. it can. The larger the YP ratio is, the higher the strength is, but if the post-processing is required, the workability is inferior. Therefore, a magnesium-based alloy wire having a YP ratio of 0.75 or more and less than 0.90 is particularly considered in terms of manufacturability. It is practical. A more preferable YP ratio is 0.80 or more and less than 0.90.
[0026]
A third feature of the magnesium-based alloy wire of the present invention is a magnesium-based alloy wire having the above-mentioned chemical composition, which has a 0.2% proof stress τ in a torsion test. _0.2 Maximum shear stress τ _max Ratio τ to _0.2 / Τ _max Is set to 0.50 or more.
[0027]
For applications where the torsional characteristics affect, such as coil springs, not only the YP ratio during tension, but also the torsional yield ratio, ie τ _0.2 / Τ _max Is important. In the present invention, at the time of drawing, the processing temperature, the rate of temperature rise to the processing temperature, the degree of processing, the linear velocity, or by performing a predetermined heat treatment after drawing, τ _0.2 / Τ _max Is 0.50 or more.
[0028]
For example, the rate of temperature rise to the processing temperature: 1 ° C./sec to 100 ° C./sec, the processing temperature: 50 ° C. or more and 200 ° C. or less (more preferably 150 ° C. or less), the degree of work: 10% or more, and the linear velocity: 1 m / By performing the drawing process in seconds or more, τ _0.2 / Τ _max Of 0.60 or more can be obtained. Further, after the above-mentioned drawing process, the substrate is cooled, and further subjected to a heat treatment at a temperature of 150 ° C. or more and 300 ° C. or less and a holding time of 5 minutes or more, so that τ _0.2 / Τ _max Can be obtained from 0.50 to less than 0.60.
[0029]
A fourth feature of the magnesium-based alloy wire of the present invention is a magnesium-based alloy wire having the above-mentioned chemical composition, wherein the average crystal grain size of the alloy constituting the wire is 10 μm or less.
[0030]
By reducing the average crystal grain size of the magnesium-based alloy to obtain a magnesium-based alloy wire having a balance between strength and toughness, post-processing such as spring processing can be easily performed. The control of the average crystal grain size is mainly performed by adjusting the processing temperature at the time of drawing.
[0031]
In particular, if a fine crystal structure having an average crystal grain size of 5 μm or less can be obtained, a magnesium-based alloy wire in which strength and toughness are further balanced can be obtained. A fine crystal structure having an average crystal grain size of 5 μm or less can be obtained by performing a heat treatment at 200 ° C. or more and 300 ° C. or less, more preferably 250 ° C. or more and 300 ° C. or less after drawing. Further, a fine crystal structure having an average crystal grain size of 4 μm or less can improve fatigue characteristics.
[0032]
The fifth feature of the magnesium-based alloy wire of the present invention is a magnesium-based alloy wire having the above-mentioned chemical composition, wherein the crystal grain size of the alloy constituting the wire has a mixed grain structure of fine crystal grains and coarse crystal grains. I did it.
[0033]
By making the crystal grains have a mixed grain structure, a magnesium-based alloy wire having both strength and toughness can be obtained. Specific examples of the mixed grain structure include a mixed structure of fine crystal grains having an average grain size of 3 μm or less and coarse crystal grains having an average grain size of 15 μm or more. Above all, by setting the area ratio of the crystal grains having an average grain size of 3 μm or less to 10% or more of the whole, a magnesium-based alloy wire having more excellent strength and toughness can be obtained. Such a mixed grain structure can be obtained by a combination of a drawing process and a heat treatment described later. In particular, the heat treatment is preferably performed at 100 to 200 ° C.
[0034]
A sixth feature of the magnesium-based alloy wire of the present invention is the magnesium-based alloy wire having the above-mentioned chemical component, wherein the alloy constituting the wire has a surface roughness of Rz ≦ 10 μm.
[0035]
By obtaining a magnesium-based alloy wire having a smooth surface, spring processing and the like can be easily performed using this wire. The control of the wire surface roughness can be performed mainly by adjusting the processing temperature at the time of drawing. In addition, the surface roughness is also affected by drawing conditions such as drawing speed and selection of lubricant.
[0036]
A seventh feature of the magnesium-based alloy wire of the present invention is a magnesium-based alloy wire having the above-mentioned chemical composition, wherein an axial residual tensile stress on the surface of the wire is set to 80 MPa or less.
[0037]
If the axial residual tensile stress on the wire surface is 80 MPa or less, it is possible to sufficiently secure the processing accuracy in deformation processing and cutting in a later step. The adjustment of the residual tensile stress in the axial direction can be adjusted by drawing conditions (temperature, degree of work) and subsequent heat treatment conditions (temperature, time). In particular, by setting the axial residual tensile stress on the wire surface to 10 MPa or less, a magnesium-based alloy wire having excellent fatigue properties can be obtained.
[0038]
An eighth feature of the magnesium-based alloy wire of the present invention is a magnesium-based alloy wire having the above-mentioned chemical composition, wherein the cyclic amplitude stress of compression and tension is 1 × 10 ⁷ This is because the fatigue strength in the case of applying once is 105 MPa or more.
[0039]
By obtaining a magnesium-based alloy wire having such fatigue characteristics, the magnesium-based alloy can be used in a wide range of fields such as springs, high-strength frames for mobile home appliances, and screws, which require high fatigue characteristics. A magnesium-based alloy wire having this fatigue characteristic can be obtained by performing a heat treatment at 150 to 250 ° C. after drawing.
[0040]
A ninth feature of the magnesium-based alloy wire of the present invention is the magnesium-based alloy wire having the above-mentioned chemical composition, wherein the wire has a diameter difference of 0.01 mm or less. The deviation in diameter is the difference between the maximum value and the minimum value of the diameter in the same cross section of the wire. By setting the diameter difference to 0.01 mm or less, the use in an automatic welding machine can be facilitated. In the spring wire, by setting the diameter difference to 0.01 mm or less, stable spring processing becomes possible, and the spring characteristics are stabilized.
[0041]
A tenth feature of the magnesium-based alloy wire of the present invention is a magnesium-based alloy wire having the above-mentioned chemical composition, wherein the wire has a non-circular cross-sectional shape.
[0042]
The cross-sectional shape of the wire is most generally circular. However, the wire of the present invention, which has excellent toughness, is not limited to a circular shape, and can be easily formed into a modified wire having an elliptical, rectangular, or polygonal cross section. A non-circular wire cross section can be easily coped with by changing the shape of the die. Such a deformed wire is suitable for application to an eyeglass frame, a frame reinforcing material of a portable electronic device, and the like.
[0043]
(Magnesium-based alloy welding wire)
The above wire can be used as a welding line. In particular, it is suitable for drawing out a welding line wound on a reel and using it in an automatic welding machine. As the welding wire, it is preferable that the chemical component is an AM-based, AZ-based, AS-based, or ZK-based magnesium alloy wire, particularly the above-described chemical components (A) to (C). Further, the wire diameter is preferably set to 0.8 to 4.0 mm. Further, the tensile strength is desirably set to 330 MPa or more. By providing such a wire diameter and tensile strength, winding and drawing as a welding wire on a reel can be performed without any trouble.
[0044]
(Magnesium-based alloy spring)
The magnesium-based alloy spring of the present invention is characterized in that the above-mentioned magnesium-based alloy wire is subjected to spring processing.
[0045]
Since the above-mentioned magnesium-based alloy wire has both strength and toughness, it can be spring-processed without any trouble. In particular, spring processing can be performed in a cold state.
[0046]
(Method of manufacturing magnesium-based alloy wire)
In the method for producing a magnesium-based alloy wire of the present invention, a step of preparing a raw material base of a magnesium-based alloy comprising any one of the chemical components (A) to (E), and drawing the raw material base. And a step of processing into a linear shape.
[0047]
According to the method of the present invention, it is possible to obtain a wire which can be easily used for post-processing such as spring processing and which can be effectively used as a reinforcing frame material for mobile home electric appliances and the like, a long welding machine, screws and the like. In particular, a wire having a length of 1000 times or more the diameter can be easily manufactured.
[0048]
As the raw material base material, a bulk material or a bar material obtained by casting or extrusion can be used. The drawing process is performed by passing the raw material base material through a hole die or a roller die. This drawing process is preferably performed at a processing temperature of 50 ° C. or higher, more preferably 100 ° C. or higher. By setting the processing temperature to 50 ° C. or higher, the processing of the wire becomes easy. However, when the processing temperature is increased, the strength is reduced, so the processing temperature is preferably 300 ° C. or less. A more preferable processing temperature is 200 ° C. or lower, and a further preferable processing temperature is 150 ° C. or lower. In the present invention, a heater is installed before the die, and the heating temperature of the heater is set as the processing temperature.
[0049]
The rate of temperature rise to the processing temperature is preferably 1 ° C./sec to 100 ° C./sec. Further, the linear speed of the drawing process is preferably 1 m / min or more.
[0050]
The drawing process can be performed in multiple stages using a plurality of hole dies or roller dies. By repeatedly performing the multi-pass drawing, a wire with a smaller diameter can be obtained. In particular, a wire having a diameter of less than 6 mm can be easily obtained.
[0051]
The cross-sectional reduction rate in one drawing process is preferably 10% or more. Since the strength obtained at a low workability is small, a wire having appropriate strength and toughness can be easily obtained by working with a cross-sectional reduction rate of 10% or more. A more preferable cross-section reduction rate per pass is 20% or more. However, since the actual processing cannot be performed if the working ratio is too large, the upper limit of the cross-sectional reduction rate per pass is about 30% or less.
[0052]
Further, it is preferable that the total cross-sectional reduction rate in the drawing process is 15% or more. A more preferable total cross-sectional reduction rate is 25% or more. By the combination of the drawing of the total cross-section reduction rate and the heat treatment described later, the metal structure can be mixed grain structure or fine crystallization, and a wire having both strength and toughness can be obtained.
[0053]
Further, the cooling rate after drawing is preferably 0.1 ° C./sec or more. Below this lower limit, the growth of crystal grains is promoted. Examples of the cooling means include a blast and the like, and the speed can be adjusted by a wind speed, an air volume, or the like.
[0054]
Further, after the drawing process, the toughness can be improved by heating the wire to 100 ° C. or more and 300 ° C. or less. A more preferable heating temperature is 150 ° C. or more and 300 ° C. or less. The holding time of the heating temperature is preferably about 5 to 20 minutes. This heat annealing promotes recovery of the strain introduced in the drawing process and recrystallization. When performing annealing after this drawing, the drawing temperature may be lower than 50 ° C. By setting the drawing temperature at about 30 ° C. or higher, the drawing itself can be performed, and thereafter, the toughness can be significantly improved by performing annealing.
[0055]
That is, by performing annealing after drawing, elongation is 12% or more, drawing is 40% or more, YP ratio is 0.75 or more and less than 0.90, and τ _0.2 / Τ _max Is suitable for obtaining a magnesium-based alloy having at least one property of 0.50 or more and less than 0.60.
[0056]
Furthermore, (1) the repetitive amplitude stress of compression and tension is 1 × 10 ⁷ Magnesium-based alloy wire with fatigue strength of 105 MPa or more when applied repeatedly, (2) Magnesium-based alloy wire with an axial residual tensile stress of 10 MPa or less on the wire surface, (3) Magnesium with an average crystal grain size of 4 μm or less In order to obtain a base alloy wire, it is preferable to perform a heat treatment at 150 to 250 ° C. after the drawing.
[0057]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
(Example 1)
An extruded material of a magnesium alloy (ASTM symbol AZ-31 alloy equivalent material) containing 3.0% by mass of Al, 1.0% by mass of Zn, and 0.15% by mass of Mn, with the balance being Mg and impurities. Using φ6.0 mm), wire drawing was performed under various conditions using a hole die to produce a wire. The processing temperature was the heating temperature of the heater installed before the hole die. The rate of temperature rise to the processing temperature is 1 to 10 ° C./sec, and the linear speed of the drawing is 2 m / min. Cooling after drawing was performed by blast cooling. The average crystal grain size was obtained by enlarging the cross-sectional structure of the wire with a microscope, measuring the grain sizes of a plurality of crystals in the visual field, and calculating the average value. The diameter of the wire after the drawing process is 4.84 to 5.85 mm (5.4 mm for processing with a 19% reduction in cross section, and 5.85 to 4.84 mm for 5 to 35% of reduction in cross section). Table 1 shows the characteristics of the wire obtained when the processing temperature was changed, and Table 2 shows the characteristics of the wire obtained when the cross-sectional reduction rate was changed.
[0058]
[Table 1]

[0059]
[Table 2]

[0060]
Referring to Table 1, the toughness of the extruded material before drawing is 19% drawing and 4.9% elongation. On the other hand, the examples of the present invention which are subjected to the drawing at a temperature of 50 ° C. or more have an aperture value of 50% or more and an elongation of 8% or more. Furthermore, the strength is higher than that before the drawing process, and high toughness is achieved with the strength increased.
[0061]
When the drawing temperature is 250 ° C. or higher, the rate of increase in strength is small. Therefore, it can be seen that at a processing temperature of 50 ° C. to 200 ° C., an excellent balance between strength and toughness is exhibited. On the other hand, drawing at a room temperature of 20 ° C. could not be performed due to disconnection.
[0062]
Referring to Table 2, the reduction and elongation are low at the reduction of 5% in the area of reduction, but at the reduction of 10% or more, the reduction of 40% or more and the elongation of 8% or more are obtained. . Further, the drawing process could not be performed at a working ratio of 35% in section reduction rate. From this, it can be seen that excellent toughness is exhibited by drawing at a working ratio of 10% or more and 30% or less.
[0063]
The obtained wire had a length of 1000 times or more of the diameter, and could be repeatedly processed in multiple passes. The average crystal grain size of each of the examples of the present invention was 10 μm or less, and the surface roughness Rz was 10 μm or less. Furthermore, when the axial residual tensile stress on the wire surface was determined by the X-ray diffraction method, all of the examples of the present invention were 80 MPa or less.
[0064]
(Example 2)
Extrusion material of a magnesium alloy (ASTM symbol AZ-61 alloy equivalent material) containing 6.4% of Al, 1.0% of Zn, and 0.28% of Mn with the balance being Mg and impurities in mass%. Using φ6.0 mm), drawing with a hole die was performed under various conditions. The processing temperature was the heating temperature of the heater installed before the hole die. The rate of temperature rise to the processing temperature is 1 to 10 ° C./sec, and the linear speed of the drawing is 2 m / min. Cooling after drawing was performed by blast cooling. The average crystal grain size was obtained by enlarging the cross-sectional structure of the wire with a microscope, measuring the grain sizes of a plurality of crystals in the visual field, and calculating the average value. The diameter of the wire after the drawing process is 4.84 to 5.85 mm (5.4 mm in a process with a cross-section reduction rate of 19%, and 5.85 to 4.84 mm in a cross-section reduction ratio of 5 to 35%). Table 3 shows the characteristics of the wire obtained when the processing temperature was changed, and Table 4 shows the characteristics of the wire obtained when the cross-sectional reduction rate was changed.
[0065]
[Table 3]

[0066]
[Table 4]

[0067]
Referring to Table 3, the toughness of the extruded material before the drawing process is as low as 15% for drawing and 3.8% for elongation. On the other hand, the examples of the present invention which are subjected to the drawing at a temperature of 50 ° C. or more have an aperture value of 50% or more and an elongation of 8% or more. Furthermore, the strength is higher than that before the drawing process, and high toughness is achieved with the strength increased.
[0068]
When the drawing temperature is 250 ° C. or higher, the rate of increase in strength is small. Therefore, it can be seen that at a processing temperature of 50 ° C. to 200 ° C., an excellent balance between strength and toughness is exhibited. On the other hand, drawing at a room temperature of 20 ° C. could not be performed due to disconnection.
[0069]
Table 4 shows that the reduction and elongation are low at a work ratio of 5% of the area reduction rate, but at a work ratio of 10% or more, a reduction of 40% or more and an elongation of 8% or more are obtained. . Further, the drawing process could not be performed at a working ratio of 35% in section reduction rate. From this, it can be seen that excellent toughness is exhibited by drawing at a working ratio of 10% or more and 30% or less.
[0070]
The obtained wire had a length of 1000 times or more of the diameter, and could be repeatedly processed in multiple passes. The average crystal grain size of each of the examples of the present invention was 10 μm or less, and the surface roughness Rz was 10 μm or less.
[0071]
(Example 3)
Spring processing was performed using the wires obtained in Examples 1 and 2 and an extruded material having the same diameter. Using a wire having a diameter of 5.0 mm, spring processing was performed with a spring outer diameter of 40 mm, and the relationship between the possibility of the spring processing and the average crystal grain size and surface roughness of the material was examined. The adjustment of the average crystal grain size and the adjustment of the surface roughness were mainly performed by adjusting the processing temperature at the time of drawing. The processing temperature in the example of the present invention is 50 to 200 ° C. The average crystal grain size was obtained by enlarging the cross-sectional structure of the wire with a microscope, measuring the grain sizes of a plurality of crystals in the visual field, and calculating the average value. The surface roughness was evaluated by Rz. Table 5 shows the results.
[0072]
[Table 5]

[0073]
(Example 4)
Extruded material (Φ6.%) Of a magnesium alloy (ASTM symbol AZ61 alloy equivalent material) containing 6.4% of Al, 1.0% of Zn, and 0.28% of Mn with the balance being Mg and impurities in mass%. 0 mm), a drawing process was performed at a processing temperature of 35 ° C. and a cross-sectional reduction rate (working degree) of 27.8%. The processing temperature was the heating temperature of the heater installed before the hole die. The rate of temperature rise to the processing temperature is 1 to 10 ° C./sec, and the linear speed of the drawing is 5 m / min. The cooling was performed by blast cooling. The cooling rate is 0.1 ° C./sec or more. As a result, the obtained wire exhibited properties of a tensile strength of 460 MPa, a draw of 15%, and an elongation of 6%. This wire was annealed at a temperature of 100 ° C. to 400 ° C. for 15 minutes, and the results of measuring the tensile properties are shown in Table 6.
[0074]
[Table 6]

[0075]
As can be seen from Table 6, although the strength is slightly reduced by annealing, the elongation and the toughness of the drawing are significantly recovered. That is, annealing at 100 to 300 ° C. after wire drawing is extremely effective in recovering toughness while maintaining a tensile strength of 330 MPa or more. Tensile strength of 300 MPa or more is obtained even at 400 ° C. annealing, and sufficient toughness is obtained. In particular, by performing annealing at 100 to 300 ° C. after drawing, a wire having excellent toughness can be obtained even at a drawing temperature of less than 50 ° C.
[0076]
(Example 5)
By using an extruded material (φ6.0 mm) of a magnesium alloy (equivalent to an ASTM symbol ZK60 alloy) containing 5.5% by mass of Zn and 0.45% of Zr, with the balance being Mg and impurities. Under the conditions described above. The processing temperature was the heating temperature of the heater installed before the hole die. The rate of temperature rise to the processing temperature is 1 to 10 ° C./sec, and the linear speed of the drawing is 5 m / min. The cooling was performed by blast cooling. The cooling rate of the example of the present invention is 0.1 ° C./sec or more. The average crystal grain size was obtained by enlarging the cross-sectional structure of the wire with a microscope, measuring the grain sizes of a plurality of crystals in the visual field, and calculating the average value. The axial residual tensile stress was determined by an X-ray diffraction method. The diameter of the wire after the drawing process is 4.84 to 5.85 mm (5.4 mm in a process with a cross-section reduction rate of 19%, and 5.85 to 4.84 mm in a cross-section reduction ratio of 5 to 35%). Table 7 shows the characteristics of the wire obtained when the processing temperature was changed, and Table 8 shows the characteristics of the wire obtained when the reduction rate of the cross section was changed.
[0077]
[Table 7]

[0078]
[Table 8]

[0079]
Referring to Table 7, the toughness of the extruded material is as low as 13% in drawing. On the other hand, in the case of the present invention, which has been subjected to drawing at a temperature of 50 ° C. or higher, the strength is 330 MPa or higher, and a significant improvement in strength is recognized. Further, it has an aperture value of 15% or more and an elongation value of 6% or more. Further, in processing at 250 ° C. or higher, the rate of increase in strength is small. Therefore, it shows an excellent strength-toughness balance at a processing temperature of 50 ° C to 200 ° C. On the other hand, the drawing at room temperature of 20 ° C. could not be performed due to disconnection.
[0080]
Table 8 shows that at a work ratio of 5%, both the drawing and the elongation are low, but at a work ratio of 10% or more, the increase in strength is remarkable. Further, the drawing process could not be performed at a working ratio of 35%. From this, a wire can be obtained by drawing at a working ratio of 10% or more and 30% or less.
[0081]
The obtained wire had a length of 1000 times or more of the diameter, and could be repeatedly processed in multiple passes. The average crystal grain size of the present invention was 10 μm or less, the surface roughness Rz was 10 μm or less, and the axial residual tensile stress was 80 MPa or less.
[0082]
(Example 6)
Spring processing was performed using the wire obtained in Example 5 and an extruded material having the same diameter. Using a wire having a wire diameter of 5.0 mm, spring processing was performed with a spring outer diameter of 40 mm, and the possibility of the spring processing and the average crystal grain size and surface roughness of the material were measured. The surface roughness was evaluated by Rz. Table 9 shows the results.
[0083]
[Table 9]

[0084]
As can be seen from Table 9, the magnesium wire having a crystal grain size of 10 μm or less and a surface roughness Rz of 10 μm or less can be spring-processed, but otherwise cannot be processed due to wire breakage during the processing. Therefore, it can be said that the magnesium-based alloy wire of the present invention having a crystal grain size of 10 μm or less and a surface roughness Rz of 10 μm or less can be subjected to spring processing.
[0085]
(Example 7)
An extruded material (φ6.0 mm) of a material equivalent to AZ31, AZ61, AZ91, and ZK60 shown below is prepared. The unit of each chemical component is mass%.
[0086]
AZ31: Al: 3.0%, Zn: 1.0%, Mn: 0.15%, the balance being Mg and impurities
AZ61: Al: 6.4%, Zn: 1.0%, Mn: 0.28%, the balance being Mg and impurities
AZ91: contains 9.0% Al, 0.7% Zn, and 0.1% Mn, with the balance being Mg and impurities
ZK60: contains 5.5% of Zn and 0.45% of Zr, with the balance being Mg and impurities
[0087]
Using these extruded materials, wire drawing was performed by a hole die at a processing temperature of 100 ° C. at a processing degree of 15 to 25% / pass to φ1.2 mm. The processing temperature was the heating temperature of the heater installed before the hole die. The rate of temperature rise to the processing temperature is 1 to 10 ° C./sec, and the linear speed of the drawing is 5 m / min. The cooling was performed by blast cooling. The cooling rate is 0.1 ° C./sec or more. At the time of drawing, the material of the present invention could obtain a long wire without breaking. The resulting wire had a length of at least 1000 times the diameter.
[0088]
Further, a tensile test, a measurement of diameter deviation and a measurement of surface roughness were performed. The deviation in diameter is the difference between the maximum value and the minimum value of the diameter in the same cross section of the wire. The surface roughness was evaluated by Rz. Table 10 shows the test results. Each characteristic of the extruded material is also shown as a comparative material.
[0089]
[Table 10]

[0090]
As shown in Table 10, the material of the present invention has a feature that the tensile strength is 300 MPa or more, the drawing is 15% or more, the elongation is 6% or more, the eccentricity difference is 0.01 mm or less, and the surface roughness Rz ≦ 10 μm. It turns out that it has.
[0091]
(Example 8)
Further, welding wires having wire diameters of φ0.8, φ1.6, and φ2.4 mm were prepared at the drawing temperatures of 50 ° C., 150 ° C., and 200 ° C. in the same manner as in Example 7, and the same evaluation was performed. . As a result, it was confirmed that each of them had features of a tensile strength of 300 MPa or more, a drawing of 15% or more, an elongation of 6% or more, a deviation diameter difference of 0.01 mm or less, and a surface roughness Rz ≦ 10 μm. .
[0092]
Further, the obtained wire was wound around a reel every 1.0 to 5.0 kg. The wire drawn from the reel has a good wire habit, and good welding can be expected by automatic welding such as manual welding, MIG, and TIG.
[0093]
(Example 9)
Using an extruded AZ-31 alloy (φ8.0 mm), a wire was drawn at a processing temperature of 100 ° C. to φ4.6 mm (10% or more in one pass, 67% in total) to obtain a wire. The processing temperature was the heating temperature of the heater installed before the hole die. The rate of temperature rise to the processing temperature is 1 to 10 ° C./sec, and the linear speed of the drawing is 2 to 10 m / min. Cooling after drawing is performed by blast cooling, and the cooling rate is 0.1 ° C./sec or more. The obtained wire was subjected to a heat treatment at 100 ° C. to 350 ° C. for 15 minutes. Table 11 shows the tensile properties. Here, those having a mixed grain structure or those having an average crystal grain size of 5 μm or less were indicated as “Examples of the present invention”.
[0094]
[Table 11]

[0095]
According to Table 11, when the heat treatment temperature is 80 ° C. or lower, the strength is high, but the elongation, drawing, and toughness are poor. The crystal structure at this time is a processed structure, and the average particle size is about 20 μm reflecting the particle size before processing.
[0096]
Further, when the heating temperature is 150 ° C. or higher, although the strength is slightly reduced, the recovery of the elongation and the drawing is remarkable, and a wire balanced in strength and toughness can be obtained. At this time, at a heating temperature of 150 ° C. and 200 ° C., the crystal structure has a mixed grain structure of crystal grains having an average particle diameter of 3 μm or less and crystal grains having an average particle diameter of 15 μm or more. At a temperature of 250 ° C. or higher, a structure in which the size of crystal grains is almost uniform is exhibited, and the average particle size is as shown in Table 11. When the average particle size is 5 μm or less, it is possible to secure a strength of 300 MPa or more.
[0097]
(Example 10)
Using an extruded material of AZ-31 alloy (φ8.0 mm), the working temperature was set to 150 ° C., and the drawing was performed by changing the total working degree at one pass working degree of 10% or more, and the obtained wire was subjected to 200 ° C. For 15 minutes, and the tensile properties of the heat-treated material were evaluated. The processing temperature of the drawing process was the heating temperature of the heater installed before the hole die. The rate of temperature rise to the processing temperature is 2 to 5 ° C./sec, and the linear speed of drawing is 2 to 5 m / min. Cooling after drawing was performed by blast cooling, and the cooling rate was 0.1 ° C./sec or more. Table 12 shows the results. Here, those having a mixed grain structure are indicated as “Examples of the present invention”.
[0098]
[Table 12]

[0099]
As can be seen from Table 12, the structure control is insufficient when the total workability is 10% or less, but when the total workability is 15% or more, a mixed structure of crystal grains having an average grain size of 3 μm or less and crystal grains having an average grain size of 15 μm or more is used. It has both high strength and high toughness.
[0100]
FIG. 1 shows a micrograph of the structure of the wire after the heat treatment at a working ratio of 23% by an optical microscope. As is clear from this photograph, it was found that the mixed structure of the crystal grains having an average particle diameter of 3 μm or less and the crystal grains having an average particle diameter of 15 μm or more was about 15%. In the case where a mixed grain structure was observed in this example, the area ratio of crystal grains of 3 μm or less was 10% or more. Further, when the total working degree is 30% or more, the strength is further increased, which is effective.
(Example 11)
Using an extruded material of ZK60 alloy (φ6.0 mm), drawing was performed to φ5.0 mm at a processing temperature of 150 ° C. (total processing degree: 30.6%). The processing temperature was the heating temperature of the heater installed before the hole die. The rate of temperature rise to the processing temperature is 2 to 5 ° C./sec, and the linear speed of drawing is 2 m / min. Cooling after drawing was performed by blast cooling, and the cooling rate was 0.1 ° C./sec or more. The cooled wire was subjected to a heat treatment at 100 ° C. to 350 ° C. for 15 minutes. Table 13 shows the tensile properties of the wire after the heat treatment. Here, those having a mixed grain structure or those having an average crystal grain size of 5 μm or less were indicated as “Examples of the present invention”.
[0101]
[Table 13]

[0102]
Table 13 shows that at a heating temperature of 80 ° C. or lower, although the strength is high, the elongation and the drawing are low, and the toughness is poor. The crystal structure at this time is a processed structure, and the particle size is more than 10 μm reflecting the particle size before processing.
[0103]
Further, when the heating temperature is 150 ° C. or higher, although the strength is slightly reduced, the recovery of the elongation and the drawing is remarkable, and a wire balanced in strength and toughness can be obtained. At this time, at a heating temperature of 150 ° C. and 200 ° C., the crystal structure has a mixed grain structure of crystal grains having an average particle diameter of 3 μm or less and crystal grains having an average particle diameter of 15 μm or more. At a temperature of 250 ° C. or higher, a structure having a uniform particle size is exhibited, and the particle size is as shown in Table 13. When the average particle size is 5 μm or less, the strength of 390 MPa or more can be secured.
[0104]
(Example 12)
Using an extruded material (φ5.0 mm) of an AZ31 alloy, an AZ61 alloy, or a ZK60 alloy, warm drawing was performed by a hole die to φ4.3 mm. The processing temperature was the heating temperature of the heater installed before the hole die. The rate of temperature rise to the processing temperature is 2 to 5 ° C./sec, and the linear speed of the drawing is 3 m / min. Cooling after drawing was performed by blast cooling, and the cooling rate was 0.1 ° C./sec or more. Tables 14 to 16 show the heating temperature and the characteristics of the obtained wire during the drawing process. The characteristics of the wire are YP ratio and torsion yield ratio τ _0.2 / Τ _max Was evaluated. The YP ratio is 0.2% proof stress / tensile strength. The torsional yield ratio is 0.2% yield strength τ in the torsional test. _0.2 Maximum shear stress τ _max Is the ratio to In the torsion test, the distance between the chucks was set to 100d (d: the diameter of the wire), and τ _0.2 And τ _max I asked. As a comparative material, the characteristics of the extruded material are also shown.
[0105]
[Table 14]

[0106]
[Table 15]

[0107]
[Table 16]

[0108]
Referring to Tables 14 to 16, the YP ratio of the extruded material is about 0.7, but in the present invention examples, the YP ratio is 0.9 or more, and the value of 0.2% proof stress is tensile. More than an increase in strength. Thus, it can be seen that effective characteristics as a structural material can be obtained.
[0109]
Also, τ _0.2 / Τ _max It can be seen that the ratio is less than 0.5 in any composition in the extruded material, but shows a high value of 0.6 or more in the examples of the present invention. This result is the same for a line or a bar having an irregular (non-circular) cross section.
[0110]
(Example 13)
Using an extruded material (φ5.0 mm) of an AZ31 alloy, an AZ61 alloy, or a ZK60 alloy, wire drawing with a hole die was performed at a temperature of 50 ° C to φ4.3 mm. The processing temperature was the heating temperature of the heater installed before the hole die. The rate of temperature rise to the processing temperature is 5 to 10 ° C./sec, and the linear speed of the drawing is 3 m / min. Cooling after drawing was performed by blast cooling, and the cooling rate was 0.1 ° C./sec or more. After the cooling, the wire is subjected to a heat treatment at 100 to 300 ° C. for 15 minutes. As a characteristic of the wire, the YP ratio and the torsion yield ratio τ are the same as in the twelfth embodiment. _0.2 / Τ _max Was evaluated. The results are shown in Tables 17 to 19. As a comparative material, the characteristics of the extruded material are also shown.
[0111]
[Table 17]

[0112]
[Table 18]

[0113]
[Table 19]

[0114]
Referring to Tables 17 to 19, the YP ratio of the extruded material is about 0.7, whereas the YP ratio of the example of the present invention subjected to the drawing and the heat treatment is 0.75 or more. Among them, it is understood that the example of the present invention in which the YP ratio is controlled to 0.75 or more and less than 0.90 has a large elongation value and good workability. If a higher strength is sought, those having a YP ratio of 0.80 or more and less than 0.90 are more preferable because they have a good balance with elongation.
[0115]
Also, the torsional yield ratio τ _0.2 / Τ _max Is less than 0.5 in any composition of the extruded material, but shows a high value of 0.50 or more when subjected to drawing and heat treatment. Considering workability, when trying to secure elongation value, τ _0.2 / Τ _max It is understood that the ratio is preferably 0.50 or more and less than 0.60.
[0116]
These results show the same tendency regardless of the composition. Further, the optimal heat treatment conditions are affected by the degree of drawing and the heating time, and differ depending on the drawing conditions. Furthermore, this result is the same for wires and rods having a cross-section that is irregular (non-circular).
[0117]
(Example 14)
Using an extruded material (φ5.0 mm) of a magnesium alloy AZ10 alloy containing Al: 1.2%, Zn: 0.4%, and Mn: 0.3% in mass%, and the balance being Mg and impurities, The drawing process was performed at a processing temperature of 100 ° C. with a total cross-sectional reduction rate of 36% (2 passes) up to φ4.0 mm. A hole die was used for this drawing. The processing temperature is such that a heater is installed before the hole die and the heating temperature of the heater is used as the processing temperature. The rate of temperature rise to the processing temperature is 10 ° C./sec, the cooling rate is 0.1 ° C./sec or more, and the linear speed of drawing is 2 m / min. Cooling after drawing was performed by blast cooling. Thereafter, the obtained linear body was subjected to a heat treatment at a temperature of 50 ° C. to 350 ° C. for 20 minutes to obtain various wires.
[0118]
Tensile strength, elongation at break, drawing, YP ratio, τ _0.2 / Τ _max The crystal grain size was investigated. The average crystal grain size was obtained by enlarging the cross-sectional structure of the wire with a microscope, measuring the grain sizes of a plurality of crystals in the visual field, and calculating the average value. The results are shown in Table 20. The extruded material of φ5.0mm has a tensile strength of 225MPa, a toughness of 38% drawing, an elongation of 9%, a YP ratio of 0.64, τ _0.2 / Τ _max The ratio is 0.55.
[0119]
[Table 20]

[0120]
As is clear from Table 20, the strength of the drawn wire is significantly improved as compared with the extruded material. Looking at the mechanical properties after the heat treatment, there is no significant change from the properties after drawing at a heating temperature of 100 ° C. or less. It can be seen that at a temperature of 150 ° C. or more, both the elongation at break and the reduction of the area greatly increase. Compared to a wire as drawn without heat treatment, tensile strength, YP ratio, τ _0.2 / Τ _max Although the ratio decreases, the tensile strength of the original extruded material, the YP ratio, τ _0.2 / Τ _max It greatly exceeds the ratio. If the heat treatment temperature exceeds 300 ° C., tensile strength, YP ratio, τ _0.2 / Τ _max An increase in the ratio is small, and a heat treatment temperature of preferably 300 ° C. or less is desired.
[0121]
As shown in Table 20, the crystal grain size of the wire obtained here is 10 μm or less at a heating temperature of 150 ° C. or more, and 5 μm or less at 200 to 250 ° C. At a temperature of 150 ° C., a mixed grain structure of crystal grains of 3 μm or less and crystal grains of 15 μm or more was obtained, and the area ratio of the crystal grains of 3 μm or less was 10% or more.
[0122]
Further, the obtained wire had a length of 1000 times or more the diameter and a surface roughness Rz of 10 μm or less. Further, when the axial residual tensile stress on the wire surface was determined by an X-ray diffraction method, the stress was 80 MPa or less. Further, the diameter difference was 0.01 mm or less. The deviation in diameter is the difference between the maximum value and the minimum value of the diameter in the same cross section of the wire.
[0123]
Then, when the obtained wire (φ4.0 mm) was subjected to spring processing at room temperature with a spring outer diameter of 35 mm, the wire of the present invention could be processed without any problem.
[0124]
(Example 15)
Using an extruded material (φ5.0 mm) of a magnesium-based alloy AZ10 alloy containing 1.2% by mass, 0.4% by mass of Zn, and 0.3% by mass of Mn, the balance being Mg and impurities in mass%. Then, drawing was performed under various conditions to obtain various wires. A hole die was used for this drawing. The processing temperature is such that a heater is installed before the hole die and the heating temperature of the heater is used as the processing temperature. The rate of temperature rise to the working temperature is 10 ° C./sec, and the linear speed of drawing is 2 m / min. Tables 21 and 22 show the characteristics of the obtained wire. Table 21 shows the conditions and results when the processing temperature was changed while the cross-sectional reduction rate was constant, and Table 22 shows the conditions and results when the cross-sectional reduction rate was changed while the processing temperature was constant. In this example, processing is performed only in one pass, and the “section reduction rate” here is the total section reduction rate.
[0125]
[Table 21]

[0126]
[Table 22]

[0127]
Referring to Table 21, the extruded material has a tensile strength of 205 MPa, a toughness of 38%, and an elongation of 9%. On the other hand, No. 1 was subjected to drawing at a temperature of 50 ° C. or higher. 1-3 to 1-9 have an aperture value of 30% or more and an elongation value of 6% or more. Furthermore, these test materials have a high tensile strength of 250 MPa or more, a YP ratio of 0.90 or more, and a τ of 0.60 or more. _0.2 / Τ _max It can be seen that the strength was improved without significantly lowering the toughness. Among them, No. 1 was subjected to drawing at a temperature of 100 ° C. or higher. 1-4 to 1-9 have an aperture value of 40% or more and an elongation value of 10% or more, and are particularly excellent in terms of toughness. On the other hand, when the drawing temperature exceeds 300 ° C., the rate of increase in strength is small, and No. 2 was subjected to drawing at room temperature of 20 ° C. No. 1-2 could not be processed due to disconnection. Therefore, at a processing temperature of 50 ° C. to 300 ° C. (preferably 100 ° C. to 300 ° C.), a better strength-toughness balance is exhibited.
[0128]
As shown in Table 22, No. 5 having a processing degree of 5%. 2-2, tensile strength, YP ratio, τ _0.2 / Τ _max The rate of increase of the ratio is small, and when the working ratio is 10% or more, the tensile strength, YP ratio, τ _0.2 / Τ _max The rate of increase of the ratio is increasing. In the case of No. 3 having a processing degree of 35%. In 2-6, the drawing process was not possible. From this fact, a high tensile strength of 250 MPa or more, a YP ratio of 0.9 or more, and a τ of 0.60 or more are obtained without reducing toughness by drawing at a workability of 10% or more and 30% or less. _0.2 / Τ _max It can be seen that excellent characteristics of the ratio are exhibited.
[0129]
The wire obtained in each of Tables 21 and 22 had a length of 1000 times or more the diameter and was capable of multi-pass repetitive drawing. Further, the surface roughness Rz was 10 μm or less. When the axial residual tensile stress on the wire surface was also determined by X-ray diffraction, the stress was 80 MPa or less. Further, the diameter difference was 0.01 mm or less. The deviation diameter difference is a difference between the maximum value and the minimum value of the diameter in the same cross section of the wire.
[0130]
Then, when the obtained wire was subjected to spring processing at room temperature with a spring outer diameter of 40 mm, the wire of the present invention could be processed without any problem.
[0131]
(Example 16)
Magnesium alloy (AS41) containing 4.2% of Al, 0.50% of Mn, 1.1% of Si, and the balance being Mg and impurities, and 6.1% of Al, Mn: 0% by mass. Using an extruded material (φ5.0 mm) of a magnesium alloy (AM60) containing 0.44% and the remainder consisting of Mg and impurities, processing was performed with a hole die having a cross-sectional reduction rate of 19% to φ4.5 mm. Table 23 shows the processing conditions and the characteristics of the obtained wire.
[0132]
[Table 23]

[0133]
Referring to Table 23, the extruded material of the AS41 alloy has a tensile strength of 259 MPa, a 0.2% proof stress of 151 MPa, and a low YP ratio of 0.58. The aperture is 19.5% and the elongation is 9.5%.
[0134]
The extruded material of the AM60 alloy also has a tensile strength of 265 MPa, a 0.2% proof stress of 160 MPa, and a low YP ratio of 0.60.
[0135]
On the other hand, those which were heated to a temperature of 150 ° C. and subjected to the drawing process had a drawing value of 30% or more and an elongation value of 6% or more for both the AS41 alloy and the AM60 alloy, and a high tensile strength of 300 MPa or more. It has strength and a YP ratio of 0.9 or more, and it can be seen that strength can be improved without significantly lowering toughness. Further, the drawing at room temperature of 20 ° C. could not be performed due to disconnection.
[0136]
(Example 17)
Magnesium alloy (AS41) containing 4.2% of Al, 0.50% of Mn, 1.1% of Si, and the balance being Mg and impurities, and 6.1% of Al, Mn: 0% by mass. Using a magnesium alloy (AM60) extruded material (φ5.0 mm) containing 0.44% and the remainder consisting of Mg and impurities, using a hole die with a 19% cross-sectional reduction rate to φ4.5 mm at a processing temperature of 150 ° C. Processing was performed. The cooling rate after this processing is 10 ° C./sec. The wire obtained at that time was heated at 80 ° C. and 200 ° C. for 15 minutes, and the tensile properties and the crystal grain size were evaluated at room temperature. Table 24 shows the results.
[0137]
[Table 24]

[0138]
After the wire drawing, the tensile strength, the 0.2% proof stress, and the YP ratio are greatly improved. Looking at the mechanical properties of the heat-treated material after drawing, there is no significant change from the properties after drawing at a processing temperature of 80 ° C. It can be seen that at a temperature of 200 ° C., both the elongation at break and the drawing were greatly increased. Although the tensile strength, 0.2% proof stress, and YP ratio are lower than those of the as-drawn material, the tensile strength, 0.2% proof stress, and YP ratio of the original extruded material greatly exceed.
[0139]
As shown in Table 24, the crystal grain size obtained at this time is a fine crystal grain of 5 μm or less at a heating temperature of 200 ° C. In addition, the obtained wire had a length of 1000 times or more the diameter, a surface roughness Rz of 10 μm or less, an axial residual tensile stress of 80 MPa or less, and a diameter difference of 0.01 mm or less.
[0140]
Further, when the obtained wire (φ4.5 mm) was subjected to spring processing at room temperature with a spring outer diameter of 40 mm, the wire of the present invention could be processed without any problem.
[0141]
(Example 18)
In mass%, a cast material of magnesium alloy (EZ33) containing 2.5% of Zn, 0.6% of Zr, 2.9% of RE, and the balance being Mg and impurities is φ5.0 mm by hot forging. And processed by a hole die having a cross-sectional reduction rate of 19% up to φ4.5 mm. Table 25 shows the processing conditions and the characteristics of the obtained wire. It should be noted that the gym is used for RE.
[0142]
[Table 25]

[0143]
Referring to Table 25, the extruded material of the EZ33 alloy has a tensile strength of 180 MPa, a 0.2% proof stress of 121 MPa, and a low YP ratio of 0.67. The drawing is 15.2% and the elongation is 4.0%.
[0144]
On the other hand, those which were heated to a temperature of 150 ° C. and subjected to drawing had a drawing value of 30% or more and an elongation value of 6% or more, a high tensile strength of 220 MPa or more, and a tensile strength of 0.9 or more. It has a YP ratio, and it can be seen that strength can be improved without significantly lowering toughness. Further, the drawing at room temperature of 20 ° C. could not be performed due to disconnection.
[0145]
(Example 19)
In mass%, a cast material of magnesium alloy (EZ33) containing 2.5% of Zn, 0.6% of Zr, 2.9% of RE, and the balance being Mg and impurities is φ5.0 mm by hot forging. And processed by a hole die having a cross-sectional reduction rate of 19% up to φ4.5 mm. The cooling rate after this processing is 10 ° C./sec. The wire obtained at that time was heated at 80 ° C. and 200 ° C. for 15 minutes, and the tensile properties and the crystal grain size were evaluated at room temperature. The results are shown in Table 26. It should be noted that the gym is used for RE.
[0146]
[Table 26]

[0147]
After the wire drawing, the tensile strength, the 0.2% proof stress, and the YP ratio are greatly improved. Looking at the mechanical properties of the heat-treated material after drawing, there is no significant change from the properties after drawing at a processing temperature of 80 ° C. It can be seen that at a temperature of 200 ° C., both the elongation at break and the drawing were greatly increased. Although the tensile strength, 0.2% proof stress, and YP ratio are lower than those of the as-drawn material, the tensile strength, 0.2% proof stress, and YP ratio of the original extruded material greatly exceed.
[0148]
As shown in Table 26, the crystal grain size obtained at this time is a fine crystal grain of 5 μm or less at a heating temperature of 200 ° C. Further, the obtained wire had a length of 1000 times or more the diameter, a surface roughness Rz of 10 μm or less, an axial residual tensile stress of 80 MPa or less, and a diameter difference of 0.01 mm or less.
[0149]
(Example 20)
By using an extruded material (φ5.0 mm) of a magnesium alloy (AS21) containing 1.9% of Al, 0.45% of Mn, and 1.0% of Si by mass%, and the balance being Mg and impurities. , And processing was performed with a hole die having a cross-sectional reduction rate of 19% to φ4.5 mm. Table 27 shows the processing conditions and the characteristics of the obtained wire.
[0150]
[Table 27]

[0151]
Referring to Table 27, the extruded material of the AS21 alloy has a tensile strength of 215 MPa, a 0.2% proof stress of 141 MPa, and a low YP ratio of 0.66.
[0152]
On the other hand, those which were heated to a temperature of 150 ° C. and subjected to drawing had a draw value of 40% or more and an elongation value of 6% or more, a high tensile strength of 250 MPa or more, and a tensile strength of 0.9 or more. It has a YP ratio, and it can be seen that strength can be improved without significantly lowering toughness. Further, the drawing at room temperature of 20 ° C. could not be performed due to disconnection.
[0153]
Further, the obtained wire had a length of 1000 times or more the diameter, a surface roughness Rz of 10 μm or less, an axial residual tensile stress of 80 MPa or less, and a diameter difference of 0.01 mm or less. Further, when the obtained wire (φ4.5 mm) was subjected to spring processing at room temperature with a spring outer diameter of 40 mm, the wire of the present invention could be processed without any problem.
[0154]
(Example 21)
Using an extruded material (φ5.0) of a magnesium alloy (AS21) containing 1.9% of Al, 0.45% of Mn, and 1.0% of Si, and the balance being Mg and impurities in mass%. At a processing temperature of 150 ° C., processing was performed with a hole die having a cross-sectional reduction rate of 19% up to φ4.5 mm. The cooling rate after this processing is 10 ° C./sec. The wire obtained at that time was heated at 80 ° C. and 200 ° C. for 15 minutes, and the tensile properties and the crystal grain size were evaluated at room temperature. The results are shown in Table 28.
[0155]
[Table 28]

[0156]
After the wire drawing, the tensile strength, the 0.2% proof stress, and the YP ratio are greatly improved. Looking at the mechanical properties of the heat-treated material after drawing, there is no significant change from the properties after drawing at a processing temperature of 80 ° C. It can be seen that at a temperature of 200 ° C., both the elongation at break and the drawing were greatly increased. Although the tensile strength, the 0.2% proof stress, and the YP ratio are lower than those of the as-drawn material, they greatly exceed the tensile strength, 0.2% proof stress, and the YP ratio of the original extruded material.
[0157]
At this time, as shown in Table 28, the obtained crystal grain size is a fine crystal grain of 5 μm or less at a heating temperature of 200 ° C. In addition, the obtained wire had a length of 1000 times or more the diameter, a surface roughness Rz of 10 μm or less, an axial residual tensile stress of 80 MPa or less, and a diameter difference of 0.01 mm or less.
[0158]
Further, when the obtained wire (φ4.5 mm) was subjected to spring processing at room temperature with a spring outer diameter of 40 mm, the wire of the present invention could be processed without any problem.
[0159]
(Example 22)
An extruded material (φ5.0 mm) of the AZ31 alloy was prepared and subjected to drawing at a processing temperature of 100 ° C. to φ4.0 mm with a surface reduction rate of 36% (two passes). The cooling rate after drawing is 10 ° C./sec. Thereafter, heat treatment was performed at a temperature of 100 ° C. to 350 ° C. for 60 minutes to obtain various wires. Then, the rotational bending fatigue strength of the wire was evaluated by a Nakamura type rotational bending fatigue test. Fatigue test is 10 ⁷ It was carried out at times. The average crystal grain size and the residual tensile stress in the axial direction of each sample were also evaluated at the same time. The results are shown in Table 29.
[0160]
[Table 29]

[0161]
As is clear from Table 29, the fatigue strength reaches a maximum of 105 MPa or more by the heat treatment at 150 ° C. or more and 250 ° C. or less. At this time, the average crystal grain size is 4 μm or less, and the axial residual tensile stress is 10 MPa or less.
[0162]
Extruded materials (φ5.0 mm) of AZ61 alloy, AS41 alloy, AM60 alloy, and ZK60 alloy were prepared, and the same evaluation was performed. The results are shown in Tables 30 to 33.
[0163]
[Table 30]

[0164]
[Table 31]

[0165]
[Table 32]

[0166]
[Table 33]

[0167]
In any of the alloy systems, a fatigue strength of 105 MPa or more is obtained by a combination of the drawing and the subsequent heat treatment, and the fatigue strength is maximized by the heat treatment of 150 ° C. or more and 250 ° C. or less. Further, the average crystal grain size is 4 μm or less, and the axial residual tensile stress is 10 MPa or less.
[0168]
【The invention's effect】
As described above, according to the method for manufacturing a wire of the present invention, it is possible to draw a magnesium alloy, which has been difficult in the past, and to obtain a magnesium-based alloy wire having excellent strength and toughness.
[0169]
Further, the magnesium-based alloy wire of the present invention has high toughness, is easy to perform post-processing such as spring processing, and is effective as a lightweight material having excellent toughness and specific strength. Therefore, wires used for reinforcing frames of MD players, CD players, mobile phones, etc. and for suitcase frames, other lightweight springs, and long welding lines and screws that can be used in automatic welding machines, etc. Is expected to be used effectively. In addition, it is expected to be used as a structural material.
[Brief description of the drawings]
FIG. 1 is a photograph of the structure of the wire of the present invention by an optical microscope.

Claims (41)

A magnesium-based alloy wire,
Obtained by drawing at 30 ~ 300 ° C.,
Consisting of a crystal structure,
With tensile strength of 220MPa or more, drawing of 15% or more, elongation of 6% or more,
A magnesium-based alloy wire comprising any one of the following chemical components (A) to (E):
(A) In mass%, Al: 0.1 to 12.0%, Mn: 0.1 to 1.0%, the balance being Mg and impurities
(B) by mass% Al: 0.1 ~ 12.0% Mn: it includes 0.1% to 1.0%, further Zn: 0.5 to 2.0% Si: includes 0.3 to 2.0% of one or more elements selected from the remainder Mg and impurities
(C) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, the balance being Mg and impurities
(D) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, Mn: 0.5 to 2.0%, the balance being Mg and impurities
(E) In mass%, Zn: 1.0 to 10.0%, rare earth element: 1.0 to 3.0%, the balance being Mg and impurities A magnesium-based alloy wire,
Obtained by drawing at 30 ~ 300 ° C.,
Consisting of a crystal structure,
Fatigue strength of 105MPa or more when 1 × 10 ⁷ repetitive amplitude stress of compression and tension is applied,
A magnesium-based alloy wire comprising any one of the following chemical components (A) to (E):
(A) In mass%, Al: 0.1 to 12.0%, Mn: 0.1 to 1.0%, the balance being Mg and impurities
(B) by mass% Al: 0.1 ~ 12.0% Mn: it includes 0.1% to 1.0%, further Zn: 0.5 to 2.0% Si: includes 0.3 to 2.0% of one or more elements selected from the remainder Mg and impurities
(C) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, the balance being Mg and impurities
(D) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, Mn: 0.5 to 2.0%, the balance being Mg and impurities
(E) In mass%, Zn: 1.0 to 10.0%, rare earth element: 1.0 to 3.0%, the balance being Mg and impurities A magnesium-based alloy wire,
Obtained by drawing at 30 ~ 300 ° C.,
Consisting of a crystal structure,
If the YP ratio is 0.75 or more,
A magnesium-based alloy wire comprising any one of the following chemical components (A) to (E):
(A) In mass%, Al: 0.1 to 12.0%, Mn: 0.1 to 1.0%, the balance being Mg and impurities
(B) by mass% Al: 0.1 ~ 12.0% Mn: it includes 0.1% to 1.0%, further Zn: 0.5 to 2.0% Si: includes 0.3 to 2.0% of one or more elements selected from the remainder Mg and impurities
(C) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, the balance being Mg and impurities
(D) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, Mn: 0.5 to 2.0%, the balance being Mg and impurities
(E) In mass%, Zn: 1.0 to 10.0%, rare earth element: 1.0 to 3.0%, the balance being Mg and impurities A magnesium-based alloy wire,
Obtained by drawing at 30 ~ 300 ° C.,
Consisting of a crystal structure,
The ratio of the 0.2% proof stress τ _{0.2 to} the maximum shear stress τ _max in the torsional test: τ _0.2 / τ _max is 0.50 or more,
A magnesium-based alloy wire comprising any one of the following chemical components (A) to (E):
(A) In mass%, Al: 0.1 to 12.0%, Mn: 0.1 to 1.0%, the balance being Mg and impurities
(B) by mass% Al: 0.1 ~ 12.0% Mn: it includes 0.1% to 1.0%, further Zn: 0.5 to 2.0% Si: includes 0.3 to 2.0% of one or more elements selected from the remainder Mg and impurities
(C) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, the balance being Mg and impurities
(D) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, Mn: 0.5 to 2.0%, the balance being Mg and impurities
(E) In mass%, Zn: 1.0 to 10.0%, rare earth element: 1.0 to 3.0%, the balance being Mg and impurities A magnesium-based alloy wire,
Obtained by drawing at 30 ~ 300 ° C.,
Consisting of a crystal structure,
0.2% proof stress τ _0.2 in torsional test is 165MPa or more,
A magnesium-based alloy wire comprising any one of the following chemical components (A) to (E):
(A) In mass%, Al: 0.1 to 12.0%, Mn: 0.1 to 1.0%, the balance being Mg and impurities
(B) by mass% Al: 0.1 ~ 12.0% Mn: it includes 0.1% to 1.0%, further Zn: 0.5 to 2.0% Si: includes 0.3 to 2.0% of one or more elements selected from the remainder Mg and impurities
(C) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, the balance being Mg and impurities
(D) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, Mn: 0.5 to 2.0%, the balance being Mg and impurities
(E) In mass%, Zn: 1.0 to 10.0%, rare earth element: 1.0 to 3.0%, the balance being Mg and impurities A magnesium-based alloy wire,
Obtained by drawing at 30 ~ 300 ° C.,
Consisting of a crystal structure,
The crystal grain size of the alloy constituting the wire is 10 μm or less,
A magnesium-based alloy wire comprising any one of the following chemical components (A) to (E):
(A) In mass%, Al: 0.1 to 12.0%, Mn: 0.1 to 1.0%, the balance being Mg and impurities
(B) by mass% Al: 0.1 ~ 12.0% Mn: it includes 0.1% to 1.0%, further Zn: 0.5 to 2.0% Si: includes 0.3 to 2.0% of one or more elements selected from the remainder Mg and impurities
(C) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, the balance being Mg and impurities
(D) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, Mn: 0.5 to 2.0%, the balance being Mg and impurities
(E) In mass%, Zn: 1.0 to 10.0%, rare earth element: 1.0 to 3.0%, the balance being Mg and impurities A magnesium-based alloy wire,
Obtained by drawing at 30 ~ 300 ° C.,
Consisting of a crystal structure,
The crystal grain size of the alloy constituting the wire is a mixed grain structure of fine crystal grains with an average grain size of 3 μm or less and coarse crystal grains with an average grain size of 15 μm or more.
A magnesium-based alloy wire comprising any one of the following chemical components (A) to (E):
(A) In mass%, Al: 0.1 to 12.0%, Mn: 0.1 to 1.0%, the balance being Mg and impurities
(B) by mass% Al: 0.1 ~ 12.0% Mn: it includes 0.1% to 1.0%, further Zn: 0.5 to 2.0% Si: includes 0.3 to 2.0% of one or more elements selected from the remainder Mg and impurities
(C) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, the balance being Mg and impurities
(D) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, Mn: 0.5 to 2.0%, the balance being Mg and impurities
(E) mass% Zn: 1.0 to 10.0% rare earth elements: comprises 1.0% to 3.0%, the balance being Mg and impurities thereof A magnesium-based alloy wire,
Obtained by drawing at 30 ~ 300 ° C.,
Consisting of a crystal structure,
When the surface roughness of the wire surface is Rz ≤ 10 μm,
A magnesium-based alloy wire comprising any one of the following chemical components (A) to (E):
(A) In mass%, Al: 0.1 to 12.0%, Mn: 0.1 to 1.0%, the balance being Mg and impurities
(B) by mass% Al: 0.1 ~ 12.0% Mn: it includes 0.1% to 1.0%, further Zn: 0.5 to 2.0% Si: includes 0.3 to 2.0% of one or more elements selected from the remainder Mg and impurities
(C) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, the balance being Mg and impurities
(D) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, Mn: 0.5 to 2.0%, the balance being Mg and impurities
(E) In mass%, Zn: 1.0 to 10.0%, rare earth element: 1.0 to 3.0%, the balance being Mg and impurities A magnesium-based alloy wire,
Obtained by drawing at 30 ~ 300 ° C.,
Consisting of a crystal structure,
When the residual tensile stress in the axial direction on the wire surface is 80 MPa or less,
A magnesium-based alloy wire comprising any one of the following chemical components (A) to (E):
(A) In mass%, Al: 0.1 to 12.0%, Mn: 0.1 to 1.0%, the balance being Mg and impurities
(B) by mass% Al: 0.1 ~ 12.0% Mn: it includes 0.1% to 1.0%, further Zn: 0.5 to 2.0% Si: includes 0.3 to 2.0% of one or more elements selected from the remainder Mg and impurities
(C) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, the balance being Mg and impurities
(D) In mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, Mn: 0.5 to 2.0%, the balance being Mg and impurities
(E) In mass%, Zn: 1.0 to 10.0%, rare earth element: 1.0 to 3.0%, the balance being Mg and impurities The magnesium-based alloy wire according to any one of claims 1 to 9, wherein the wire is drawn at 50 ° C or higher. The magnesium-based alloy wire according to any one of claims 1 to 10, wherein the length L is 1000d or more with respect to the diameter d. 12. The magnesium-based alloy wire according to claim 11, wherein the diameter d is 0.1 mm or more and 10.0 mm or less. The magnesium-based alloy wire according to any one of claims 1 to 12, wherein the tensile strength is 250 MPa or more. The magnesium-based alloy wire according to any one of claims 1 to 12, wherein the tensile strength is 300 MPa or more. The magnesium-based alloy wire according to any one of claims 1 to 12, wherein the drawing is 30% or more. 13. The magnesium-based alloy wire according to claim 1, wherein the drawing is 40% or more. The magnesium-based alloy wire according to any one of claims 1 to 12, wherein the elongation is 6% or more and less than 12%. The magnesium-based alloy wire according to any one of claims 1 to 12, wherein the elongation is 12% or more. 13. The magnesium-based alloy wire according to claim 1, wherein a YP ratio is 0.75 or more and less than 0.90. The magnesium-based alloy wire according to any one of claims 1 to 12, wherein the YP ratio is 0.90 or more. 13. The magnesium-based alloy wire according to claim 1, wherein the ratio τ _0.2 / τ _max is 0.50 or more and less than 0.60. 13. The magnesium-based alloy wire according to claim 1, wherein the ratio τ _0.2 / τ _max is 0.60 or more. 13. The magnesium-based alloy wire according to claim 1, wherein an axial residual tensile stress on the wire surface is 10 MPa or less. 13. The magnesium-based alloy wire according to claim 1, wherein a crystal grain size of an alloy forming the wire is 5 μm or less. 8. The magnesium-based alloy wire according to claim 7, wherein an area ratio of crystal grains having an average grain size of 3 μm or less is 10% or more of the whole. 13. The magnesium-based alloy wire according to claim 1, wherein the wire has a non-circular cross-sectional shape. The magnesium-based alloy wire according to any one of claims 1 to 12, wherein a deviation in diameter of the wire is 0.01 mm or less. 13. The magnesium-based alloy wire according to claim 1, wherein the chemical component is (A) or (B) and the content of Al is 0.1 to less than 2.0%. The magnesium-based alloy wire according to any one of claims 1 to 12, wherein the chemical component is (A) or (B) and the content of Al is 2.0% or more. A magnesium-based alloy spring obtained by subjecting the magnesium-based alloy wire according to claim 1 to spring processing. The magnesium-based alloy wire according to any one of claims 1 to 29, wherein the wire is a welding wire having a diameter of 0.8 to 4.0 mm. A step of preparing a raw material base material of a magnesium-based alloy having a crystal structure composed of any of the following (A) to (E) chemical components,
(A) Magnesium-based alloy base material containing, by mass%, Al: 0.1 to 12.0% and Mn: 0.1 to 1.0%, with the balance being Mg and impurities
(B) by mass% Al: 0.1 ~ 12.0% Mn: it includes 0.1% to 1.0%, further Zn: 0.5 to 2.0% Si: includes 0.3 to 2.0% of one or more elements selected from the remainder Magnesium base alloy base material consisting of Mg and impurities
(C) Magnesium base alloy base material containing, by mass%, Zn: 1.0 to 10.0% and Zr: 0.4 to 2.0%, with the balance being Mg and impurities
(D) Magnesium base alloy base material containing, by mass%, Zn: 1.0 to 10.0%, Zr: 0.4 to 2.0%, further containing Mn: 0.5 to 2.0%, and the balance being Mg and impurities
(E) Magnesium-based alloy base material containing 1.0 to 10.0% of Zn, 1.0 to 3.0% of rare earth element and the balance being Mg and impurities by mass%, and drawing the above base material at 30 to 300 ° C. And a step of processing the wire into a linear shape. The method for producing a magnesium-based alloy wire according to claim 32, wherein the drawing temperature is 50 ° C or more and 300 ° C or less. 33. The method for producing a magnesium-based alloy wire according to claim 32, wherein a cross-sectional reduction rate in one drawing is 10% or more. 33. The method for producing a magnesium-based alloy wire according to claim 32, wherein a total cross-sectional reduction rate in the drawing process is 15% or more. 33. The method for producing a magnesium-based alloy wire according to claim 32, wherein a linear velocity of the drawing is 1 m / min or more. 33. The method for producing a magnesium-based alloy wire according to claim 32, wherein the rate of temperature rise to the drawing temperature is 1 ° C / sec to 100 ° C / sec. 33. The method for producing a magnesium-based alloy wire according to claim 32, wherein the drawing is performed by a hole die or a roller die. 33. The method for producing a magnesium-based alloy wire according to claim 32, wherein the drawing is performed in multiple stages using a plurality of hole dies or roller dies. 33. The method for producing a magnesium-based alloy wire according to claim 32, wherein the drawing is performed at less than 50 ° C. 41. The method for producing a magnesium-based alloy wire according to claim 32, wherein the obtained linear body is heated to a temperature of 100 ° C. or more and 300 ° C. or less after drawing.

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